MLK-22556-1 spi: flexspi_nand: Add new flexspi nand driver

MLK-22556-1 spi: flexspi_nand: Add new flexspi nand driver

Add flexspi_nand driver which works on iMX flexspi controller to support
SPI NAND flash. This driver requires DM_SPI and follows SPI-MEM interfaces
to adapt to the SPI NAND framework.

Note: Current implementation limits to the 12-bit column address. This is
popular in main stream SPI NAND and flash devices supported in u-boot.
If device with larger page size (> 4096) needs to support, we have to change
the driver.

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit d5c2580a245fa0cd4ae0012ceb5c8bd2f497f19c)
(cherry picked from commit a56bf035b87d9fe1352c9a8293f91c9026552b1e)