ieee802154: mcr20a: Remove dead Kconfig symbols
ieee802154: mcr20a: Remove dead Kconfig symbols

We have moved GPIO info to DT so the Kconfig symbols for GPIO lines
aren't used anymore.  We can just remove them.

Signed-off-by: Kumar Gala <a5e5248af4cd4f0ed8c515f61d40a6e2db46a66e@linaro.org>

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