arm: Move tbl to arch_global_data

Move this field into arch_global_data and tidy up.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/cpu/arm926ejs/at91/timer.c b/arch/arm/cpu/arm926ejs/at91/timer.c
index f691518..4443fef 100644
--- a/arch/arm/cpu/arm926ejs/at91/timer.c
+++ b/arch/arm/cpu/arm926ejs/at91/timer.c
@@ -80,7 +80,7 @@
 	writel(TIMER_LOAD_VAL | AT91_PIT_MR_EN , &pit->mr);
 
 	gd->arch.timer_rate_hz = gd->arch.mck_rate_hz / 16;
-	gd->arch.tbu = gd->tbl = 0;
+	gd->arch.tbu = gd->arch.tbl = 0;
 
 	return 0;
 }
@@ -95,10 +95,10 @@
 	ulong now = readl(&pit->piir);
 
 	/* increment tbu if tbl has rolled over */
-	if (now < gd->tbl)
+	if (now < gd->arch.tbl)
 		gd->arch.tbu++;
-	gd->tbl = now;
-	return (((unsigned long long)gd->arch.tbu) << 32) | gd->tbl;
+	gd->arch.tbl = now;
+	return (((unsigned long long)gd->arch.tbu) << 32) | gd->arch.tbl;
 }
 
 void __udelay(unsigned long usec)