ENGR00213170-2 [MX6SL] Enable GPU driver

ENGR00213170-2 [MX6SL] Enable GPU driver

Use allocated GPU resource to enable GPU.
Memroy address on imx6sl board starts from 0x80000000
and GC320 can access [baseAddress, baseAddress + 2G) only without MMU.
So to make GC320 work, baseAddres must be set to 0x80000000, and all
address sent to GC320 must be a offset to baseAddress. GC355 doesn't
need this baseAddress, that means it needs a real physcial adress,
rather than the offset to baseAddress.
Original code always change phsysical address to 'offset' before use it,
no matter it is used by GC355 or GC320, so only one of them can work.
Solution is to move address adjustion to arch specific part. So each
core can get what it wants.

Signed-off-by: Larry Li <b20787@freescale.com>
Acked-by: Lily Zhang