spi: atmel-quadspi: Drop superfluous set of QSPI_IFR_APBTFRTYP_READ

That bit describes the APB transfer type. We are writing
serial memory registers via AHB acesses, that bit does not
make sense in the current context.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20201207135959.154124-3-tudor.ambarus@microchip.com


Signed-off-by: Mark Brown <broonie@kernel.org>