drm/amd/powerplay: fix uninitialized variable

refresh_rate was not initialized when program
display gap.
this patch can fix vce ring test failed
when do S3 on Polaris10.

bug: https://bugs.freedesktop.org/show_bug.cgi?id=103102
bug: https://bugzilla.kernel.org/show_bug.cgi?id=196615Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NRex Zhu <Rex.Zhu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/powerplay/hwmgr/smu7_hwmgr.c

@@ -830,7 +830,7 @@ uint32_t smu7_get_xclk(struct pp_hwmgr *hwmgr)
 {
 	uint32_t reference_clock, tmp;
 	struct cgs_display_info info = {0};
-	struct cgs_mode_info mode_info;
+	struct cgs_mode_info mode_info = {0};
 
 	info.mode_info = &mode_info;
 
@@ -3948,10 +3948,9 @@ static int smu7_program_display_gap(struct pp_hwmgr *hwmgr)
 	uint32_t ref_clock;
 	uint32_t refresh_rate = 0;
 	struct cgs_display_info info = {0};
-	struct cgs_mode_info mode_info;
+	struct cgs_mode_info mode_info = {0};
 
 	info.mode_info = &mode_info;
-
 	cgs_get_active_displays_info(hwmgr->device, &info);
 	num_active_displays = info.display_count;
 
@@ -3967,6 +3966,7 @@ static int smu7_program_display_gap(struct pp_hwmgr *hwmgr)
 	frame_time_in_us = 1000000 / refresh_rate;
 
 	pre_vbi_time_in_us = frame_time_in_us - 200 - mode_info.vblank_time_us;
+
 	data->frame_time_x2 = frame_time_in_us * 2 / 100;
 
 	display_gap2 = pre_vbi_time_in_us * (ref_clock / 100);