Add xen PVCALLS to the config

Enable XEN_PVCALLS_FRONTEND & XEN_PVCALLS_BACKEND

Signed-off-by: Sai Hari Chandana Kalluri <chandana.kalluri@xilinx.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

features/xen/xen.cfg

@@ -43,3 +43,5 @@ CONFIG_XEN_PRIVCMD=y
 CONFIG_XEN_ACPI_PROCESSOR=m
 CONFIG_XEN_MCE_LOG=y
 CONFIG_XEN_HAVE_PVMMU=y
+CONFIG_XEN_PVCALLS_FRONTEND=y
+CONFIG_XEN_PVCALLS_BACKEND=y