spi: Fix SPI NOR and SPI NAND acronyms

The industry refers to these flash types as "SPI NOR" and
"SPI NAND". Be consistent and use the same acronyms.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/r/20200716051144.568606-1-tudor.ambarus@microchip.com


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