mtd: spi-nor: sysfs: print JEDEC ID for generic flash driver

We don't have a database entry for the generic SPI-NOR flash driver and
thus we don't have a JEDEC ID to print. Print the (cached) JEDEC ID
instead.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Link: https://lore.kernel.org/r/20220810220654.1297699-8-michael@walle.cc