drivers: flash: spi nor: Allow the init priority to be configurable

Some applications may require the SPI NOR driver to be initialized
earlier. This commit enables the user to change the default
initialization priority.

Signed-off-by: Vidar Berg <vidar.berg@nordicsemi.no>

drivers/flash/Kconfig.nor

@@ -45,7 +45,7 @@ config SPI_NOR_SFDP_RUNTIME
 endchoice
 
 config SPI_NOR_INIT_PRIORITY
-	int
+	int "Init priority"
 	default 80
 	help
 	  Device driver initialization priority.