ARM: configs: at91: sama7: Enable NAND / SMC

Enable the Static Memory Controller. Tested with Micron MT29F4G08ABAEAWP
NAND flash. Software error correction is not needed, as the SMC includes
a PMECC error correction hardware module.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20220111125641.903624-1-tudor.ambarus@microchip.com