arm: Move lastinc 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/mx27/timer.c b/arch/arm/cpu/arm926ejs/mx27/timer.c
index 06e3086..07e132a 100644
--- a/arch/arm/cpu/arm926ejs/mx27/timer.c
+++ b/arch/arm/cpu/arm926ejs/mx27/timer.c
@@ -46,7 +46,7 @@
 DECLARE_GLOBAL_DATA_PTR;
 
 #define timestamp	(gd->arch.tbl)
-#define lastinc		(gd->lastinc)
+#define lastinc		(gd->arch.lastinc)
 
 /*
  * "time" is measured in 1 / CONFIG_SYS_HZ seconds,