The Micron mt25qu02g supports both x2 and x4 transactions. Add the
SPI_NOR_DUAL_READ flag to its spi_nor_ids[] table entry.

Tested on Pensando SoC hardware with a cadence quadspi controller
via drivers/spi/spi-cadence-quadspi.c, in x2 mode at 50MHz.
  - random data write, erase, read   - verified erase operations
  - random data write, read/compare  - verified write/read operations
Signed-off-by: David Clear <dac2@pensando.io>
Acked-by: Shannon Nelson <snelson@pensando.io>
Link: https://lore.kernel.org/r/20200720163656.38006-3-dac2@pensando.ioSigned-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>