coverage: kernel: poll: Cleanup redundant code to improve coverage
coverage: kernel: poll: Cleanup redundant code to improve coverage

Remove few redundant code in kernel polling interface.

Signed-off-by: Praful Swarnakar <b56c70d8c3b21a158307ccd68a699c2a05d34cb8@intel.com>

nashif/zephyr,Vudentz/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,punitvara/zephyr,finikorg/zephyr,explora26/zephyr,kraj/zephyr,explora26/zephyr,galak/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,explora26/zephyr,punitvara/zephyr,punitvara/zephyr,punitvara/zephyr,ldts/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,explora26/zephyr,galak/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,GiulianoFranchetto/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,kraj/zephyr,Vudentz/zephyr,kraj/zephyr,ldts/zephyr,nashif/zephyr,galak/zephyr,ldts/zephyr