drivers: flash: atmel sam0: Fix compilation without page layout support
drivers: flash: atmel sam0: Fix compilation without page layout support

The sam0 flash driver has support for retrieving flash page layout
information.  This commit fixes compilation when
CONFIG_FLASH_PAGE_LAYOUT is disabled.

Signed-off-by: Henrik Brix Andersen <a076b11c2cc63ccdc903dbe182e1eecc3cbbc094@brixandersen.dk>

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