mtd: spi-nor: spansion: s25fl256s0: Skip SFDP parsing

s25fl256s0 does not define the SFDP tables nor implements the
RDSFDP 0x5a command. Skip the SFDP parsing in order to avoid
issuing an unsupported command to the flash.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20211207140254.87681-13-tudor.ambarus@microchip.com