drm/amd/display: Fix UBSAN warning for not a valid value for type '_Bool'

[Why]
dc_cursor_position do not initialise position.translate_by_source when
crtc or plane->state->fb is NULL. UBSAN caught this error in
dce110_set_cursor_position, as the value was garbage.

[How]
Initialise dc_cursor_position structure elements to 0 in handle_cursor_update
before calling get_cursor_position.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1471Reported-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Anson Jacob <Anson.Jacob@amd.com>
Reviewed-by: Aurabindo Jayamohanan Pillai <Aurabindo.Pillai@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -7521,10 +7521,6 @@ static int get_cursor_position(struct drm_plane *plane, struct drm_crtc *crtc,
 	int x, y;
 	int xorigin = 0, yorigin = 0;
 
-	position->enable = false;
-	position->x = 0;
-	position->y = 0;
-
 	if (!crtc || !plane->state->fb)
 		return 0;
 
@@ -7571,7 +7567,7 @@ static void handle_cursor_update(struct drm_plane *plane,
 	struct dm_crtc_state *crtc_state = crtc ? to_dm_crtc_state(crtc->state) : NULL;
 	struct amdgpu_crtc *amdgpu_crtc = to_amdgpu_crtc(crtc);
 	uint64_t address = afb ? afb->address : 0;
-	struct dc_cursor_position position;
+	struct dc_cursor_position position = {0};
 	struct dc_cursor_attributes attributes;
 	int ret;