spi: atmel-quadspi: Write QSPI_IAR only when needed

The address must be written in QSPI_IAR only when we have
a instruction frame with address but no data.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20201207135959.154124-4-tudor.ambarus@microchip.com


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