Unix: Cleanup to use ACPI_TO_INTEGER() to calc page offset.

The offset calculation doesn't need to convert a pointer to a special
integer type. So this patch uses ACPI_TO_INTEGER() instead.

Signed-off-by: Lv Zheng <lv.zheng@intel.com>

source/os_specific/service_layers/osunixmap.c

@@ -238,6 +238,6 @@ AcpiOsUnmapMemory (
 
 
     PageSize = AcpiOsGetPageSize ();
-    Offset = (ACPI_PHYSICAL_ADDRESS) Where % PageSize;
+    Offset = ACPI_TO_INTEGER (Where) % PageSize;
     munmap ((UINT8 *) Where - Offset, (Length + Offset));
 }