spi: spi-fsl-qspi: Ensure width is respected in spi-mem operations

spi: spi-fsl-qspi: Ensure width is respected in spi-mem operations

[ Upstream commit b0177aca7aea7e8917d4e463334b51facb293d02 ]

Make use of a core helper to ensure the desired width is respected
when calling spi-mem operators.

Otherwise only the SPI controller will be matched with the flash chip,
which might lead to wrong widths. Also consider the width specified by
the user in the device tree.

Fixes: 84d043185dbe ("spi: Add a driver for the Freescale/NXP QuadSPI controller")
Signed-off-by: Michael Walle <michael@walle.cc>
Link: https://lore.kernel.org/r/20200114154613.8195-1-michael@walle.cc
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>