Kernel: Add method to clean up remapping region loops

In the VMObject code there are multiple examples of loops over
the VMObject's regions (using for_each_region()) that call remap()
on each region.

To clean up usage of this pattern, this patch adds a method in
VMObject that does this remapping loop. VMObject code that needs
to remap its regions call the new method.

Kernel/Memory/InodeVMObject.cpp

@@ -59,11 +59,8 @@ int InodeVMObject::release_all_clean_pages()
             ++count;
         }
     }
-    if (count) {
-        for_each_region([](auto& region) {
-            region.remap();
-        });
-    }
+    if (count)
+        remap_regions();
     return count;
 }
 
@@ -78,11 +75,8 @@ int InodeVMObject::try_release_clean_pages(int page_amount)
             ++count;
         }
     }
-    if (count) {
-        for_each_region([](auto& region) {
-            region.remap();
-        });
-    }
+    if (count)
+        remap_regions();
     return count;
 }