xtensa: Switch do_timer() to xtime_update()

xtime_update() takes the xtime_lock itself.

set_linux_timer() does not need to be protected by xtime_lock.

[ tglx: This code is broken on SMP anyway. ]

Signed-off-by: Torben Hohn <torbenh@gmx.de>
Cc: Chris Zankel <chris@zankel.net>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: johnstul@us.ibm.com
Cc: hch@infradead.org
Cc: yong.zhang0@gmail.com
LKML-Reference: <20110127150027.23248.61798.stgit@localhost>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/xtensa/kernel/time.c

@@ -96,16 +96,12 @@ again:
 		update_process_times(user_mode(get_irq_regs()));
 #endif
 
-		write_seqlock(&xtime_lock);
-
-		do_timer(1); /* Linux handler in kernel/timer.c */
+		xtime_update(1); /* Linux handler in kernel/time/timekeeping */
 
 		/* Note that writing CCOMPARE clears the interrupt. */
 
 		next += CCOUNT_PER_JIFFY;
 		set_linux_timer(next);
-
-		write_sequnlock(&xtime_lock);
 	}
 
 	/* Allow platform to do something useful (Wdog). */