mtd: spinand: Use the spi-mem dirmap API

mtd: spinand: Use the spi-mem dirmap API

Make use of the spi-mem direct mapping API to let advanced controllers
optimize read/write operations when they support direct mapping.

Based on a linux commit 981d1aa0697c ("mtd: spinand: Use the spi-mem dirmap API")
created by Boris Brezillon <bbrezillon@kernel.org> with additional
fixes taken from Linux 6.10.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>