ENGR00274782 fixed gpu crash when baseAddress is not 0 or 2G

The baseAddress of contiguousVidMem is the actual physical address
which is not subtracted by gpu baseAddress, but the allocated physical address
has been subtracted by gpu baseAddress in gckVIDMEM_Lock,
so the invalid offset is produced and used to calculate the logical address.

Signed-off-by: Xianzhong <b07117@freescale.com>
Acked-by: Shawn Guo
ENGR00277045-1 fix system reboot with video playback

gpu virtual memory cannot be allocated for external use

this issue occurs in ARD board with 2G above memory address

Signed-off-by: Xianzhong <b07117@freescale.com>
Acked-by: Jason Liu
ENGR00277045-2 align gpu baseaddr with ram base address

2G above address will be converted to gpu virtual address in i.MX6,
gpu baseaddr can be used to reduce contiguous memory address conversion,
the benifit for gpu applications and external memory consumers(VPU/IPU) have,
 - gpu mmu performance penalty is reduce in most cases,
 - more system memory can be exported for external use

Signed-off-by: Xianzhong <b07117@freescale.com>