Add cpu/8xxx to TAGS_SUBDIRS

Signed-off-by: Ed Swarthout <Ed.Swarthout@freescale.com>

Makefile

@@ -243,9 +243,11 @@ endif
 ifeq ($(CPU),mpc85xx)
 LIBS += drivers/qe/qe.a
 LIBS += cpu/mpc8xxx/ddr/libddr.a
+TAG_SUBDIRS += cpu/mpc8xxx
 endif
 ifeq ($(CPU),mpc86xx)
 LIBS += cpu/mpc8xxx/ddr/libddr.a
+TAG_SUBDIRS += cpu/mpc8xxx
 endif
 LIBS += drivers/rtc/librtc.a
 LIBS += drivers/serial/libserial.a