mtd: spi-nor: Fix the writing of the Status Register on micron flashes

mtd: spi-nor: Fix the writing of the Status Register on micron flashes

Micron flashes do not support 16 bit writes on the Status Register.
According to micron datasheets, when using the Write Status Register
(01h) command, the chip select should be driven LOW and held LOW until
the eighth bit of the last data byte has been latched in, after which
it must be driven HIGH. If CS is not driven HIGH, the command is not
executed, flag status register error bits are not set, and the write enable
latch remains set to 1. This fixes the lock operations on micron flashes.

Reported-by: John Garry <john.garry@huawei.com>
Fixes: 39d1e3340c73 ("mtd: spi-nor: Fix clearing of QE bit on lock()/unlock()")
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Tested-by: John Garry <john.garry@huawei.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>