drm/amd/powerplay: fixed uninitialized value

The 'result' is not initialized correctly. It causes the API
return an error code even on success.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/amd/powerplay/hwmgr/vega12_hwmgr.c

@@ -488,7 +488,7 @@ static int vega12_get_number_of_dpm_level(struct pp_hwmgr *hwmgr,
 static int vega12_get_dpm_frequency_by_index(struct pp_hwmgr *hwmgr,
 		PPCLK_e clkID, uint32_t index, uint32_t *clock)
 {
-	int result;
+	int result = 0;
 
 	/*
 	 *SMU expects the Clock ID to be in the top 16 bits.