drivers: flash: sam: Fix driver support

The current atmel sam flash driver was develop based on the cortex-m7
version of smart arm microcontroller. The driver support write
protection and cache functions which is not supported by other cortex-m
variants. This fixes current driver implementation and devicetree
entries for all sam variants.

Notes:
 * The cortex-m3 doesn't have support erase pages flash command and
   because of that the driver still not not compatible. Keep it disabled
   until a patch be send. The hwinfo driver is not affected by this
   restriction.
 * The sam4l variation requires a specific driver because uses another
   flash controller (flashcalw). Added another compatible to
   differentiate and keeped node disabled until a driver be available.

Fixes #48516

Signed-off-by: Gerson Fernando Budke <nandojve@gmail.com>