mtd: spi-nor: remove mtk-quadspi driver

This driver is superseded by the new spi-mtk-nor driver.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Acked-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20200306085052.28258-5-gch981213@gmail.com


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