cris: arch-v10: Switch do_timer() to xtime_update()

cris: arch-v10: Switch do_timer() to xtime_update()

This code failed to take the xtime_lock, which must be held when
calling do_timer(). Use the safe version xtime_update()

Signed-off-by: Torben Hohn <torbenh@gmx.de>
Cc: hch@infradead.org
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: johnstul@us.ibm.com
Cc: Mikael Starvik <starvik@axis.com>
Cc: yong.zhang0@gmail.com
LKML-Reference: <20110127145936.23248.16192.stgit@localhost>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>