[POWERPC] MPC832x_RDB: Update dts to use SPI1 in QE, register mmc_spi stub

Enabled using SPI controller on the MPC832x RDB board.  We currently use
a modalias of "spidev" as a place holder (replace with "mmc_spie") until
the mmc_spi driver support is merged in.

This gets us the ability to test SPI until then.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>