net_pkt: Reordering the attributes for better alignment
net_pkt: Reordering the attributes for better alignment

Instead of using a bool, let's just use a bit in a bifield, shared among
various attribute. This saves space.

Make ext_len attribute enabled only on IPv6 (ipv6, icmpv6 and rpl are
the only code setting it) and reordering the helpers functions
accordingly.

Change-Id: Ifd3295d778959308ead7db9b2a59396e50f8e18c
Signed-off-by: Tomasz Bursztyka <ba81a3a719836727e6857ae83462b9f52ec41006@linux.intel.com>

punitvara/zephyr,fbsder/zephyr,fractalclone/zephyr-riscv,finikorg/zephyr,pklazy/zephyr,holtmann/zephyr,pklazy/zephyr,finikorg/zephyr,bigdinotech/zephyr,mbolivar/zephyr,fractalclone/zephyr-riscv,Vudentz/zephyr,explora26/zephyr,Vudentz/zephyr,explora26/zephyr,rsalveti/zephyr,rsalveti/zephyr,holtmann/zephyr,punitvara/zephyr,sharronliu/zephyr,aceofall/zephyr-iotos,nashif/zephyr,finikorg/zephyr,rsalveti/zephyr,punitvara/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,zephyriot/zephyr,galak/zephyr,erwango/zephyr,runchip/zephyr-cc3220,mbolivar/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,bigdinotech/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,galak/zephyr,bigdinotech/zephyr,bboozzoo/zephyr,rsalveti/zephyr,bboozzoo/zephyr,ldts/zephyr,aceofall/zephyr-iotos,rsalveti/zephyr,erwango/zephyr,sharronliu/zephyr,bboozzoo/zephyr,sharronliu/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,nashif/zephyr,sharronliu/zephyr,fractalclone/zephyr-riscv,zephyrproject-rtos/zephyr,fbsder/zephyr,nashif/zephyr,zephyriot/zephyr,explora26/zephyr,runchip/zephyr-cc3220,erwango/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,mbolivar/zephyr,zephyriot/zephyr,zephyriot/zephyr,holtmann/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,fbsder/zephyr,holtmann/zephyr,mbolivar/zephyr,aceofall/zephyr-iotos,fbsder/zephyr,runchip/zephyr-cc3220,ldts/zephyr,pklazy/zephyr,galak/zephyr,kraj/zephyr,galak/zephyr,holtmann/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,mbolivar/zephyr,finikorg/zephyr,bboozzoo/zephyr,nashif/zephyr,fractalclone/zephyr-riscv,bboozzoo/zephyr,kraj/zephyr,bigdinotech/zephyr,sharronliu/zephyr,nashif/zephyr,bigdinotech/zephyr,finikorg/zephyr,kraj/zephyr,Vudentz/zephyr,ldts/zephyr,fractalclone/zephyr-riscv,fbsder/zephyr,pklazy/zephyr,erwango/zephyr,zephyriot/zephyr,Vudentz/zephyr,punitvara/zephyr,runchip/zephyr-cc3220,runchip/zephyr-cc3220,erwango/zephyr,kraj/zephyr,aceofall/zephyr-iotos,pklazy/zephyr