ARM: davinci: da850: changed SRAM allocator to shared ram.

This patch modifies the sram allocator to allocate memory
from the DA8XX shared RAM.

Regression tested suspend/resume on AM180x EVM.

Signed-off-by: Subhasish Ghosh <subhasish@mistralsolutions.com>
[rebased onto consolidated SRAM patches]
Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
[rebased to mainline as consolidated SRAM patches were dropped]
Signed-off-by: Matt Porter <mporter@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>