board: cssi: Fix SPI nodes in DTS

board: cssi: Fix SPI nodes in DTS

When adding additional SPI peripherals, the reg property needs to
be added, and this leads to the following error:

  arch/powerpc/dts/cmpc885.dtb: Warning (reg_format): /immr@ff000000/spi@aa0/temp@1:reg: property has invalid length (4 bytes) (#address-cells == 1, #size-cells == 1)
  arch/powerpc/dts/cmpc885.dtb: Warning (reg_format): /immr@ff000000/spi@aa0/temp@2:reg: property has invalid length (4 bytes) (#address-cells == 1, #size-cells == 1)

Fix it by removing cell-index and cell-size which is unused and add
reg property. Also fix node name to be in line with reg value.
Also add missing compatible for eeprom node.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>