mtd: nand: raw: atmel: Fix comment in timings preparation

Introduced with commit 6a8dfd57 ("nand: atmel: Add DM based NAND
driver") when driver was initially ported from Linux.  The context
around this and especially the code itself suggests 'read' is meant
instead of write.

The fix is the same as accepted in Linux already with mainline Linux
kernel commit 1c60e027ffde ("mtd: nand: raw: atmel: Fix comment in
timings preparation").

Link: https://lore.kernel.org/all/20240320090214.40465-6-ada@thorsis.com
Link: https://lore.kernel.org/linux-mtd/20240307172835.3453880-1-miquel.raynal@bootlin.com/T/#t


Signed-off-by: Alexander Dahl <ada@thorsis.com>
Reviewed-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>