drm/amd/pm: Remove wm_low and wm_high fields from amdgpu_crtc (v2)

These fields were only used by si_dpm and are not necessary
anymore. They also may have been incorrect because:
- wm_high was set to the LOW_WATERMARK field of watermark A.
- wm_low was not set on DCE 6 and was always zero.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h

@@ -496,8 +496,6 @@ struct amdgpu_crtc {
 	struct drm_connector *connector;
 	/* for dpm */
 	u32 line_time;
-	u32 wm_low;
-	u32 wm_high;
 	u32 lb_vblank_lead_lines;
 	struct drm_display_mode hw_mode;
 	/* for virtual dce */