drm/amd/display: Disable cursor when offscreen in negative direction

[Why]
When x or y is negative we set the x and y values to 0 and compensate
with a positive cursor hotspot in DM since DC expects positive cursor
values.

When x or y is less than or equal to the maximum cursor width or height
the cursor hotspot is clamped so the hotspot doesn't exceed the
cursor size:

if (x < 0) {
        xorigin = min(-x, amdgpu_crtc->max_cursor_width - 1);
        x = 0;
}

if (y < 0) {
        yorigin = min(-y, amdgpu_crtc->max_cursor_height - 1);
        y = 0;
}

This incorrectly forces the cursor to be at least 1 pixel on the screen
in either direction when x or y is sufficiently negative.

[How]
Just disable the cursor when it goes far enough off the screen in one
of these directions.

This fixes kms_cursor_crc@cursor-256x256-offscreen.
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Sun peng Li <Sunpeng.Li@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -4945,12 +4945,12 @@ static int get_cursor_position(struct drm_plane *plane, struct drm_crtc *crtc,
 	int x, y;
 	int xorigin = 0, yorigin = 0;
 
-	if (!crtc || !plane->state->fb) {
-		position->enable = false;
-		position->x = 0;
-		position->y = 0;
+	position->enable = false;
+	position->x = 0;
+	position->y = 0;
+
+	if (!crtc || !plane->state->fb)
 		return 0;
-	}
 
 	if ((plane->state->crtc_w > amdgpu_crtc->max_cursor_width) ||
 	    (plane->state->crtc_h > amdgpu_crtc->max_cursor_height)) {
@@ -4964,6 +4964,10 @@ static int get_cursor_position(struct drm_plane *plane, struct drm_crtc *crtc,
 	x = plane->state->crtc_x;
 	y = plane->state->crtc_y;
 
+	if (x <= -amdgpu_crtc->max_cursor_width ||
+	    y <= -amdgpu_crtc->max_cursor_height)
+		return 0;
+
 	if (crtc->primary->state) {
 		/* avivo cursor are offset into the total surface */
 		x += crtc->primary->state->src_x >> 16;