drm/amdgpu: fix compiler warning

Fixes below warning:
drivers/gpu/drm/amd/amdgpu/df_v3_6.c: In function ‘df_v3_6_reset_perfmon_cntr’:
drivers/gpu/drm/amd/amdgpu/df_v3_6.c:571:2: warning: ‘hi_base_addr’ may be used
uninitialized in this function [-Wmaybe-uninitialized]
  571 |  df_v3_6_perfmon_wreg(adev, lo_base_addr, 0, hi_base_addr, 0);
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/df_v3_6.c

@@ -560,7 +560,7 @@ static void df_v3_6_pmc_release_cntr(struct amdgpu_device *adev,
 static void df_v3_6_reset_perfmon_cntr(struct amdgpu_device *adev,
 					 uint64_t config)
 {
-	uint32_t lo_base_addr, hi_base_addr;
+	uint32_t lo_base_addr = 0, hi_base_addr = 0;
 
 	df_v3_6_pmc_get_read_settings(adev, config, &lo_base_addr,
 				      &hi_base_addr);