dts: add label property to all jedec,spi-nor nodes

The property is required on all SPI clients, but was missing from
several devicetree nodes.  Set it, using the capitalized version of the
node alias when present, with "jedec,spi-nor#0" as the fallback.

Closes #17662

Signed-off-by: Peter A. Bigot <pab@pabigot.com>