wayland-drm: add missing NULL check

Although malloc is unlikely to fail check its return value nevertheless.

Signed-off-by: Frank Binns <frank.binns@imgtec.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

src/egl/wayland/wayland-drm/wayland-drm.c

@@ -265,6 +265,8 @@ wayland_drm_init(struct wl_display *display, char *device_name,
 	struct wl_drm *drm;
 
 	drm = malloc(sizeof *drm);
+	if (!drm)
+		return NULL;
 
 	drm->display = display;
 	drm->device_name = strdup(device_name);