drm/amdgpu: Use correct SRIOV macro for gmc_v9_0_vm_fault_interrupt_state

Under SRIOV, programming to VM_CONTEXT*_CNTL regs failed because the
current macro does not pass through the correct xcc instance.
Use the *REG32_XCC macro in this case.

The behaviour without SRIOV is the same without this patch.

Signed-off-by: Victor Lu <victorchengchi.lu@amd.com>
Reviewed-by: Zhigang Luo <Zhigang.Luo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>