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/arm1136/mx31/timer.c b/arch/arm/cpu/arm1136/mx31/timer.c
index 86916d1..790bab4 100644
--- a/arch/arm/cpu/arm1136/mx31/timer.c
+++ b/arch/arm/cpu/arm1136/mx31/timer.c
@@ -117,11 +117,11 @@
 
 	if (now >= gd->lastinc)	/* normal mode (non roll) */
 		/* move stamp forward with absolut diff ticks */
-		gd->tbl += (now - gd->lastinc);
+		gd->arch.tbl += (now - gd->lastinc);
 	else			/* we have rollover of incrementer */
-		gd->tbl += (0xFFFFFFFF - gd->lastinc) + now;
+		gd->arch.tbl += (0xFFFFFFFF - gd->lastinc) + now;
 	gd->lastinc = now;
-	return gd->tbl;
+	return gd->arch.tbl;
 }
 
 ulong get_timer_masked(void)