mtd: spi-nor: Add a RWW flag

mtd: spi-nor: Add a RWW flag

[ Upstream commit 4eddee70140b3ae183398b246a609756546c51f1 ]

Introduce a new (no SFDP) flag for the feature that we are about to
support: Read While Write. This means, if the chip has several banks and
supports RWW, once a page of data to write has been transferred into the
chip's internal SRAM, another read operation happening on a different
bank can be performed during the tPROG delay.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230328154105.448540-7-miquel.raynal@bootlin.com
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Stable-dep-of: 9fd0945fe6fa ("mtd: spi-nor: spansion: Enable JFFS2 write buffer for Infineon s28hx SEMPER flash")
Signed-off-by: Sasha Levin <sashal@kernel.org>