Cosmetic changes to nanokernel initialization code
Cosmetic changes to nanokernel initialization code

1) Revises name of background/idle task stack area to make it
   more meaningful.
2) Converts a routine to be non-global since it isn't used elsewhere,
   and renames it to remove an unneeded leading underscore.
3) Updates and enhances comments to better reflect the current
   operation of nanokernel initialization.

Change-Id: Ibff7703562d1a9585dc2022741a6f0acb90c0a78
Signed-off-by: Allan Stephens <1038bc33971d2c23c8e2eee8dd6938c077db52dc@windriver.com>

tidyjiang8/zephyr-doc,zephyrproject-rtos/zephyr,punitvara/zephyr,kraj/zephyr,bboozzoo/zephyr,coldnew/zephyr-project-fork,runchip/zephyr-cc3200,bigdinotech/zephyr,rsalveti/zephyr,punitvara/zephyr,zephyriot/zephyr,erwango/zephyr,zephyriot/zephyr,32bitmicro/zephyr,holtmann/zephyr,fbsder/zephyr,bigdinotech/zephyr,nashif/zephyr,erwango/zephyr,runchip/zephyr-cc3220,mbolivar/zephyr,kraj/zephyr,erwango/zephyr,32bitmicro/zephyr,runchip/zephyr-cc3200,fbsder/zephyr,erwango/zephyr,pklazy/zephyr,ldts/zephyr,pklazy/zephyr,mbolivar/zephyr,32bitmicro/zephyr,zephyrproject-rtos/zephyr,bigdinotech/zephyr,pklazy/zephyr,rsalveti/zephyr,sharronliu/zephyr,fbsder/zephyr,mirzak/zephyr-os,galak/zephyr,explora26/zephyr,bboozzoo/zephyr,nashif/zephyr,Vudentz/zephyr,zephyriot/zephyr,Vudentz/zephyr,erwango/zephyr,sharronliu/zephyr,galak/zephyr,mbolivar/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,kraj/zephyr,aceofall/zephyr-iotos,pklazy/zephyr,tidyjiang8/zephyr-doc,runchip/zephyr-cc3220,mbolivar/zephyr,mirzak/zephyr-os,GiulianoFranchetto/zephyr,finikorg/zephyr,rsalveti/zephyr,Vudentz/zephyr,runchip/zephyr-cc3220,fbsder/zephyr,bigdinotech/zephyr,fractalclone/zephyr-riscv,runchip/zephyr-cc3200,finikorg/zephyr,kraj/zephyr,fractalclone/zephyr-riscv,Vudentz/zephyr,mbolivar/zephyr,aceofall/zephyr-iotos,32bitmicro/zephyr,Vudentz/zephyr,fractalclone/zephyr-riscv,holtmann/zephyr,zephyriot/zephyr,mirzak/zephyr-os,coldnew/zephyr-project-fork,nashif/zephyr,tidyjiang8/zephyr-doc,coldnew/zephyr-project-fork,jamesonwilliams/zephyr-kernel,holtmann/zephyr,mirzak/zephyr-os,tidyjiang8/zephyr-doc,punitvara/zephyr,mirzak/zephyr-os,tidyjiang8/zephyr-doc,sharronliu/zephyr,rsalveti/zephyr,bigdinotech/zephyr,pklazy/zephyr,runchip/zephyr-cc3220,holtmann/zephyr,runchip/zephyr-cc3220,jamesonwilliams/zephyr-kernel,aceofall/zephyr-iotos,sharronliu/zephyr,fractalclone/zephyr-riscv,finikorg/zephyr,nashif/zephyr,finikorg/zephyr,ldts/zephyr,galak/zephyr,explora26/zephyr,punitvara/zephyr,jamesonwilliams/zephyr-kernel,explora26/zephyr,ldts/zephyr,bboozzoo/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,32bitmicro/zephyr,ldts/zephyr,explora26/zephyr,runchip/zephyr-cc3200,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,aceofall/zephyr-iotos,jamesonwilliams/zephyr-kernel,jamesonwilliams/zephyr-kernel,fbsder/zephyr,runchip/zephyr-cc3200,bboozzoo/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,holtmann/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,coldnew/zephyr-project-fork,finikorg/zephyr,coldnew/zephyr-project-fork,zephyriot/zephyr,fractalclone/zephyr-riscv,sharronliu/zephyr,nashif/zephyr,ldts/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr,bboozzoo/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,rsalveti/zephyr