spi: airoha: fix dirmap_{read,write} operations

spi: airoha: fix dirmap_{read,write} operations

SPI_NFI_READ_FROM_CACHE_DONE bit must be written at the end of
dirmap_read operation even if it is already set.
In the same way, SPI_NFI_LOAD_TO_CACHE_DONE bit must be written at the
end of dirmap_write operation even if it is already set.
For this reason use regmap_write_bits() instead of regmap_set_bits().
This patch fixes mtd_pagetest kernel module test.

Fixes: a403997c1201 ("spi: airoha: add SPI-NAND Flash controller driver")
Tested-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20240913-airoha-spi-fixes-v1-1-de2e74ed4664@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>