spi: atmel: Switch to transfer_one transfer method

[ Upstream commit 5fa5e6de ]

Switch from using our own transfer_one_message routine to using the one
provided by the SPI core.

Signed-off-by: Dan Sneddon <dan.sneddon@microchip.com>
Link: https://lore.kernel.org/r/20210602160816.4890-1-dan.sneddon@microchip.com


Signed-off-by: Mark Brown <broonie@kernel.org>
Stable-dep-of: fc70d643 ("spi: atmel: Fix clock issue when using devices with different polarities")
Signed-off-by: Sasha Levin <sashal@kernel.org>