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/davinci/timer.c b/arch/arm/cpu/arm926ejs/davinci/timer.c
index e28e6e3..b620bf7 100644
--- a/arch/arm/cpu/arm926ejs/davinci/timer.c
+++ b/arch/arm/cpu/arm926ejs/davinci/timer.c
@@ -74,11 +74,11 @@
 	unsigned long now = readl(&timer->tim34);
 
 	/* increment tbu if tbl has rolled over */
-	if (now < gd->tbl)
+	if (now < gd->arch.tbl)
 		gd->arch.tbu++;
-	gd->tbl = now;
+	gd->arch.tbl = now;
 
-	return (((unsigned long long)gd->arch.tbu) << 32) | gd->tbl;
+	return (((unsigned long long)gd->arch.tbu) << 32) | gd->arch.tbl;
 }
 
 ulong get_timer(ulong base)