drivers: spi: Align nrfx_spi shim with the nrfx_spim one
drivers: spi: Align nrfx_spi shim with the nrfx_spim one

Similar parts of code are aligned in the two shims, so that they
can be easily compared and updated if required.

Signed-off-by: Andrzej Głąbek <6788b8d556a8a447102338fc996c42180ecff44e@nordicsemi.no>

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