drm/amd/powerplay/tonga: disable uvd pg

BugLink: http://bugs.launchpad.net/bugs/1546572

Not working reliably yet.
Reviewed-by: Eric Huang <JinHuiEric.Huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 3d5afb41)
Signed-off-by: Alberto Milone <alberto.milone@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/gpu/drm/amd/powerplay/hwmgr/tonga_hwmgr.c

@@ -4615,6 +4615,9 @@ int tonga_hwmgr_backend_init(struct pp_hwmgr *hwmgr)
 
 	data->vddc_phase_shed_control = 0;
 
+	phm_cap_unset(hwmgr->platform_descriptor.platformCaps,
+		      PHM_PlatformCaps_UVDPowerGating);
+
 	if (0 == result) {
 		struct cgs_system_info sys_info = {0};