[PATCH 1/2][MIPS] replace c0_compare acknowledge by c0_timer_ack()

[Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>]

VR41xx, CP0 hazard is necessary between read_c0_count() and write_c0_compare().
However, the problem can be solved by replacing this by c0_timer_ack(). 

Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>

diff -pruN -X /home/yuasa/Memo/dontdiff linux-orig/arch/mips/kernel/cevt-r4k.c 
linux/arch/mips/kernel/cevt-r4k.c
--- linux-orig/arch/mips/kernel/cevt-r4k.c      2008-03-11 10:10:09.453835304 
+0900
+++ linux/arch/mips/kernel/cevt-r4k.c   2008-03-12 16:35:42.911447048 +0900
@@ -186,7 +186,7 @@ static int c0_compare_int_usable(void)
         * IP7 already pending?  Try to clear it by acking the timer.
         */
        if (c0_compare_int_pending()) {
-               write_c0_compare(read_c0_count());
+               c0_timer_ack();
                irq_disable_hazard();
                if (c0_compare_int_pending())
                        return 0;
@@ -198,7 +198,7 @@ static int c0_compare_int_usable(void)
                write_c0_compare(cnt);
                irq_disable_hazard();
                if ((int)(read_c0_count() - cnt) < 0)
-                   break;
+                       break;
                /* increase delta if the timer was already expired */
        }
 
@@ -208,7 +208,7 @@ static int c0_compare_int_usable(void)
        if (!c0_compare_int_pending())
                return 0;
 
-       write_c0_compare(read_c0_count());
+       c0_timer_ack();
        irq_disable_hazard();
        if (c0_compare_int_pending())
                return 0;