[POWERPC] ep8248e: Reference SMC parameter RAM base in the device tree.

This patch modifies the Embedded Planet EP8248E device tree to reference the
SMC paramater RAM base register instead of the parameter RAM allocated by the
boot loader.

The cpm_uart driver will allocate parameter RAM itself, making the serial port
initialisation independent of the boot loader.

The patch adds the parameter RAM allocated by the boot loader in the CPM muram
node, making it available to the kernel.

Signed-off-by: Laurent Pinchart <laurentp@cse-semaphore.com>
Acked-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>