This patch adds interface to allocate memory pool for smu.
This memory pool will be used for SMC use and msg SetSystemVirtualDramAddr and
DramLogSetDramAddr can notify it changed.

v2: add detailed info to describe this function
Signed-off-by: Huang Rui <ray.huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>