drm/amdgpu: Add stolen reserved memory for MI25 SRIOV.

MI25 SRIOV guest driver loading failed due to allocated memory overlaps
with firmware reserved area.
Allocate stolen reserved memory for MI25 SRIOV specifically to avoid the
memory overlap.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>