drm/amdgpu: add an option to allow gpu partition allocate all available memory

drm/amdgpu: add an option to allow gpu partition allocate all available memory

Current driver reports and limits memory allocation for each partition equally
among partitions using same memory partition. Application may not be able to
use all available memory when run on a partitioned gpu though system still has
enough free memory.

Add an option that app can use to have gpu partition allocate all available
memory.

Signed-off-by: Xiaogang Chen <xiaogang.chen@amd.com>
Reviewed-by: Philip Yang <philip.yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>