Bluetooth: L2CAP: Refactor handling connection response
Bluetooth: L2CAP: Refactor handling connection response

Adds internal helper routine sending response to connection request when
BR/EDR CoC channel operates in acceptor role. The routine additionally
can drive the response 'result' value for failure reasons.
Use it then to adjust 'l2cap_br_conn_pend' function to accept remote's
connection request.

Change-Id: I906e07e30939c57b206e9806426897f6e4f2b3dd
Signed-off-by: Arkadiusz Lichwa <a8f3d827a064762faaf15c916aaf7025632f7d7f@tieto.com>

aceofall/zephyr-iotos,zephyrproject-rtos/zephyr,rsalveti/zephyr,punitvara/zephyr,bboozzoo/zephyr,aceofall/zephyr-iotos,rsalveti/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,tidyjiang8/zephyr-doc,holtmann/zephyr,zephyrproject-rtos/zephyr,pklazy/zephyr,fractalclone/zephyr-riscv,Vudentz/zephyr,aceofall/zephyr-iotos,explora26/zephyr,zephyriot/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,runchip/zephyr-cc3200,fractalclone/zephyr-riscv,ldts/zephyr,fractalclone/zephyr-riscv,erwango/zephyr,explora26/zephyr,bigdinotech/zephyr,runchip/zephyr-cc3220,galak/zephyr,galak/zephyr,sharronliu/zephyr,bboozzoo/zephyr,bboozzoo/zephyr,bboozzoo/zephyr,kraj/zephyr,Vudentz/zephyr,zephyriot/zephyr,zephyriot/zephyr,pklazy/zephyr,ldts/zephyr,zephyriot/zephyr,fractalclone/zephyr-riscv,erwango/zephyr,punitvara/zephyr,finikorg/zephyr,aceofall/zephyr-iotos,mbolivar/zephyr,rsalveti/zephyr,galak/zephyr,erwango/zephyr,galak/zephyr,aceofall/zephyr-iotos,holtmann/zephyr,fbsder/zephyr,finikorg/zephyr,ldts/zephyr,punitvara/zephyr,Vudentz/zephyr,mbolivar/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,rsalveti/zephyr,runchip/zephyr-cc3200,GiulianoFranchetto/zephyr,runchip/zephyr-cc3200,tidyjiang8/zephyr-doc,runchip/zephyr-cc3220,finikorg/zephyr,mbolivar/zephyr,fbsder/zephyr,tidyjiang8/zephyr-doc,mbolivar/zephyr,runchip/zephyr-cc3200,erwango/zephyr,Vudentz/zephyr,sharronliu/zephyr,sharronliu/zephyr,holtmann/zephyr,pklazy/zephyr,pklazy/zephyr,zephyrproject-rtos/zephyr,fbsder/zephyr,nashif/zephyr,explora26/zephyr,fbsder/zephyr,galak/zephyr,punitvara/zephyr,rsalveti/zephyr,runchip/zephyr-cc3220,kraj/zephyr,tidyjiang8/zephyr-doc,nashif/zephyr,kraj/zephyr,kraj/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,tidyjiang8/zephyr-doc,runchip/zephyr-cc3200,bboozzoo/zephyr,bigdinotech/zephyr,sharronliu/zephyr,erwango/zephyr,ldts/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,zephyriot/zephyr,sharronliu/zephyr,GiulianoFranchetto/zephyr,runchip/zephyr-cc3220,fbsder/zephyr,bigdinotech/zephyr,explora26/zephyr,pklazy/zephyr,holtmann/zephyr,punitvara/zephyr,fractalclone/zephyr-riscv,bigdinotech/zephyr,finikorg/zephyr,kraj/zephyr,runchip/zephyr-cc3220,mbolivar/zephyr,GiulianoFranchetto/zephyr,holtmann/zephyr,bigdinotech/zephyr