drm/radeon/dpm: implement vblank_too_short callback for CI

Check if we can switch the mclk during the vblank time otherwise
we may get artifacts on the screen when the mclk changes.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_asic.h

@@ -767,6 +767,7 @@ void ci_dpm_debugfs_print_current_performance_level(struct radeon_device *rdev,
 						    struct seq_file *m);
 int ci_dpm_force_performance_level(struct radeon_device *rdev,
 				   enum radeon_dpm_forced_level level);
+bool ci_dpm_vblank_too_short(struct radeon_device *rdev);
 
 int kv_dpm_init(struct radeon_device *rdev);
 int kv_dpm_enable(struct radeon_device *rdev);