drm/amdgpu remove restriction of sriov max_pfn on Vega10

Remove restriction of sriov max_pfn so that TBA and TMA can move to high
47 bits address.

Regression test: change range alloc flag of libdrm as
AMDGPU_VA_RANGE_HIGH and there is no flr occur when testing amdgpu_test
of drm.

Signed-off-by: Lin.Cao <lincao12@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>