Fix subtotal not updating (vuematerial#625)

Author: d3radicated

src/components/mdTable/mdTablePagination.vue

@@ -54,6 +54,9 @@
     },
     watch: {
       mdTotal(val) {
+        const sub = this.currentPage * this.currentSize;
+
+        this.subTotal = sub > val ? val : sub;
         this.totalItems = isNaN(val) ? Number.MAX_SAFE_INTEGER : parseInt(val, 10);
       },
       mdSize(val) {