drivers: nrf_qspi_nor: Mark driver with FLASH_HAS_EXPLICIT_ERASE

All QSPI connected NOR Flash devices require erase prior to
write.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

drivers/flash/Kconfig.nordic_qspi_nor

@@ -7,6 +7,7 @@ menuconfig NORDIC_QSPI_NOR
 	depends on DT_HAS_NORDIC_QSPI_NOR_ENABLED
 	select FLASH_HAS_DRIVER_ENABLED
 	select FLASH_HAS_PAGE_LAYOUT
+	select FLASH_HAS_EXPLICIT_ERASE
 	select NRFX_QSPI
 	select FLASH_JESD216
 	select PINCTRL