arm: Move tbu 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/include/asm/global_data.h b/arch/arm/include/asm/global_data.h
index eb8c69a..47fa4c0 100644
--- a/arch/arm/include/asm/global_data.h
+++ b/arch/arm/include/asm/global_data.h
@@ -37,6 +37,7 @@
 #endif
 	/* "static data" needed by most of timer.c on ARM platforms */
 	unsigned long timer_rate_hz;
+	unsigned long tbu;
 };
 
 /*
@@ -64,7 +65,6 @@
 #ifdef CONFIG_ARM
 	/* "static data" needed by most of timer.c on ARM platforms */
 	unsigned long	tbl;
-	unsigned long	tbu;
 	unsigned long long	timer_reset_value;
 	unsigned long	lastinc;
 #endif