spi: atmel-quadspi: Remove duplicated DTR checks

spi: atmel-quadspi: Remove duplicated DTR checks

Remove the DTR checks as they are already handled in
spi_mem_default_supports_op(). This code removal was intentionally not done
in the previous patch that introduced the use of the
spi_mem_default_supports_op() core helper and fixed the buswidth adjustment
between SPIMEM and the SPI controller, so that the fix can be easily
backported to stable kernels.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20220406133604.455356-2-tudor.ambarus@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.org>