MGS-791 [#1818] Unmaped virtural address cause MMU exception

In the original GPU driver, there is no way to map the virtual memory
dynamically. All the MMU table is built on beginning. However, there is
a chance that the system alloc the memory whoes address is beyond the
original MMU table region. When such kind of virtual address is passed
to GPU, there will be MMU excetion because of lacking necessary mapping.

This patch adds the case of gcvFEATURE_MMU in the hardware feature check
function. So that the virtual memory can be mapped dynamically.

Date July 14, 2015

Signed-off-by: Shawn Xiao <b49994@freescale.com>