ARM: mmp: register internal sram bank

MMP2 have the internal sram, this sram can be allocated
for video, power management and secure processor.

Now the sram usage is:
0xd1000000 ~ 0xd101ffff (128KB) : reserved for secure processor
0xd1020000 ~ 0xd1037fff (96KB)  : for video and PM

Register the internal sram's second half 96KB buffer,
so that video and PM can dynamically alloc/free from it.

Signed-off-by: Leo Yan <leoy@marvell.com>
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>