dts: enable the SEEPROM and SPI bus

This SEEPROM is used by the Wii U to store decryption keys and various other stuff, see https://wiiubrew.org/wiki/Hardware/SEEPROM

The code change is there to make the 93xx46 driver work on the 93c66 instead, which is obviously not upstreamable. This should probably get refactored into supporting both 93c46, 93c56 and 93c66 before merging.

Signed-off-by: Emmanuel Gil Peyrot linkmauve@linkmauve.fr