Cleanup: Remove unused argument from modifier data mask callback

This isn't likely to be helpful in the future with the move to generic
attributes

source/blender/modifiers/intern/MOD_surfacedeform.c

@@ -192,9 +192,7 @@ static void initData(ModifierData *md)
   MEMCPY_STRUCT_AFTER(smd, DNA_struct_default_get(SurfaceDeformModifierData), modifier);
 }
 
-static void requiredDataMask(Object *UNUSED(ob),
-                             ModifierData *md,
-                             CustomData_MeshMasks *r_cddata_masks)
+static void requiredDataMask(ModifierData *md, CustomData_MeshMasks *r_cddata_masks)
 {
   SurfaceDeformModifierData *smd = (SurfaceDeformModifierData *)md;