drm/amdgpu/smu: add metrics table lock

This table is used for lots of things, add it's own lock.

Bug: https://gitlab.freedesktop.org/drm/amd/issues/900
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/powerplay/amdgpu_smu.c

@@ -872,6 +872,7 @@ static int smu_sw_init(void *handle)
 	smu->smu_baco.platform_support = false;
 
 	mutex_init(&smu->sensor_lock);
+	mutex_init(&smu->metrics_lock);
 
 	smu->watermarks_bitmap = 0;
 	smu->power_profile_mode = PP_SMC_POWER_PROFILE_BOOTUP_DEFAULT;