MX51EVK: fix return value of get_timer_masked

get_timer_masked() should return current timestamp,
not current ticks from hardware register.

Tested on one custom board with NAND flash.
Without this patch, NAND write always TIMEOUT
because get_timer(0) return a big value.

This patch applies for u-boot-2010.06
Signed-off-by: NLi Haibo <hbli@sinocastel.com>

arch/arm/cpu/armv7/mx51/timer.c

@@ -89,7 +89,7 @@ ulong get_timer_masked(void)
 		timestamp += ((0xFFFFFFFF / (CONFIG_MX51_CLK32 / CONFIG_SYS_HZ))
 				- lastinc) + val;
 	lastinc = val;
-	return val;
+	return timestamp;
 }
 
 ulong get_timer(ulong base)