mtd: spi-nor: winbond: add "w/ and w/o SFDP" comment

mtd: spi-nor: winbond: add "w/ and w/o SFDP" comment

Commit d35df77707bf ("mtd: spi-nor: winbond: fix w25q128 regression")
upstream fixed a regression for flavors of 0xef4018 flash that don't
define SFDP tables. Add a comment on the flash definition highlighting
that there are flavors of flashes with and without SFDP support.
It spares developers searching the entire git log for when we'll better
handle these cases.

Acked-by: Pratyush Yadav <pratyush@kernel.org>
Link: https://lore.kernel.org/r/20241029080049.96679-1-tudor.ambarus@linaro.org
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>