drm/amd/powerplay: disable engine spread spectrum feature on Vega10.

Vega10 atomfirmware do not have ASIC_InternalSS_Info table
so disable this feature by default in driver.
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Reviewed-by: Ken Wang <Qingqing.wang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/hwmgr/vega10_hwmgr.c

@@ -1535,7 +1535,11 @@ static int vega10_populate_single_gfx_level(struct pp_hwmgr *hwmgr,
 	current_gfxclk_level->FbMult =
 			cpu_to_le32(dividers.ulPll_fb_mult);
 	/* Spread FB Multiplier bit: bit 0:8 int, bit 31:16 frac */
+	if (phm_cap_enabled(hwmgr->platform_descriptor.platformCaps,
+				PHM_PlatformCaps_EngineSpreadSpectrumSupport))
 		current_gfxclk_level->SsOn = dividers.ucPll_ss_enable;
+	else
+		current_gfxclk_level->SsOn = 0;
 	current_gfxclk_level->SsFbMult =
 			cpu_to_le32(dividers.ulPll_ss_fbsmult);
 	current_gfxclk_level->SsSlewFrac =