mtd: spi-nor: move the .id and .id_len into an own structure

Create a new structure to hold a flash ID and its length. The goal is to
have a new macro SNOR_ID() which can have a flexible id length. This way
we can get rid of all the individual INFOx() macros.

Signed-off-by: Michael Walle <mwalle@kernel.org>
Link: https://lore.kernel.org/r/20230807-mtd-flash-info-db-rework-v3-13-e60548861b10@kernel.org


Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>