ARM: dts: aspeed: rainier: Remove SPI NOR controllers

Early Rainier builds had SPI NOR as a fallback boot device when eMMC
was not programmed. Most systems don't have the NOR populated, so remove
it from the device tree as it is not used.

Signed-off-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20220120063307.63898-1-joel@jms.id.au
Signed-off-by: Joel Stanley <joel@jms.id.au>