arm: extend pvclock_wall_clock with sec_hi

The hypervisor actually exposes an additional field to struct
pvclock_wall_clock, with the high 32 bit seconds.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NJulien Grall <julien.grall@citrix.com>

arch/arm/include/asm/xen/interface.h

@@ -78,6 +78,7 @@ struct pvclock_wall_clock {
 	u32   version;
 	u32   sec;
 	u32   nsec;
+	u32   sec_hi;
 } __attribute__((__packed__));
 #endif