dt-bindings: mtd: spi-nor: add optional interrupts property

Some spi flash memories have an interrupt signal which can be used for
signalling on-chip events such as busy status or ecc errors to the host.

Add binding for "interrupts" property so that boards wiring this signal
may describe the connection.

Signed-off-by: Josua Mayer <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Acked-by: Pratyush Yadav <[e-mail]>
Acked-by: Michael Walle <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Tudor Ambarus <[e-mail]>

Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml

···
     minItems: 1
     maxItems: 2
 
+  interrupts:
+    maxItems: 1
+
   m25p,fast-read:
     type: boolean
     description: