drm/amd/display: Fix null check for pipe_ctx->plane_state in resource_build_scaling_params

Null pointer dereference issue could occur when pipe_ctx->plane_state
is null. The fix adds a check to ensure 'pipe_ctx->plane_state' is not
null before accessing. This prevents a null pointer dereference.

Found by code review.

Fixes: 3be5262e353b ("drm/amd/display: Rename more dc_surface stuff to plane_state")
Reviewed-by: Alex Hung <[e-mail]>
Signed-off-by: Ma Ke <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>
(cherry picked from commit 63e6a77ccf239337baa9b1e7787cde9fa0462092)
Cc: [e-mail]

drivers/gpu/drm/amd/display/dc/core/dc_resource.c

···
 	DC_LOGGER_INIT(pipe_ctx->stream->ctx->logger);
 
 	/* Invalid input */
-	if (!plane_state->dst_rect.width ||
+	if (!plane_state ||
+			!plane_state->dst_rect.width ||
 			!plane_state->dst_rect.height ||
 			!plane_state->src_rect.width ||
 			!plane_state->src_rect.height) {