ENGR00240988: gpu: allocate contiguous memory from CMA for 3.10 kernel

ENGR00240988: gpu: allocate contiguous memory from CMA for 3.10 kernel

The Contiguous Memory Allocator (CMA) is mature in 3.10 kernel.  Let's
change gpu driver to allocate contiguous memory from CMA pool.  Doing so
will save not only the memblock reserve calls in machine code but also
the request_mem_region() and ioremap() in gpu driver.  And all the
system memory will be seen by kernel no matter whether gpu driver is
running or not.

It also changes the default contiguousSize to 128 MiB for Freescale
adjustment.

Signed-off-by: Shawn Guo <shawn.guo@freescale.com>