MMFMWK-7996 waylandsink: set waylandsink to mscale 845s default sink

upstream status: imx specific
diff --git a/ext/wayland/gstwaylandsink.c b/ext/wayland/gstwaylandsink.c
index c30c9e7..71001ce 100644
--- a/ext/wayland/gstwaylandsink.c
+++ b/ext/wayland/gstwaylandsink.c
@@ -1031,6 +1031,8 @@
   if (HAS_DPU()) {
     if (HAS_VPU())
       rank = IMX_GST_PLUGIN_RANK + 1;
+  } else if (IS_IMX8MM()) {
+      rank = IMX_GST_PLUGIN_RANK + 1;
   } else if (HAS_DCSS()) {
     rank = IMX_GST_PLUGIN_RANK;
   }