gdsys: mpc8308: Use shadow register for output GPIO values

Since the gpio output status on MPC8xxx cannot be read back, it has to
be buffered locally.

Signed-off-by: Dirk Eibach <dirk.eibach@gdsys.cc>
Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/board/gdsys/mpc8308/mpc8308.h b/board/gdsys/mpc8308/mpc8308.h
index dc07d56..1e4f24f 100644
--- a/board/gdsys/mpc8308/mpc8308.h
+++ b/board/gdsys/mpc8308/mpc8308.h
@@ -1,6 +1,9 @@
 #ifndef __MPC8308_H_
 #define __MPC8308_H_
 
+void setbits_gpio0_out(u32 mask);
+void clrbits_gpio0_out(u32 mask);
+
 /* functions to be provided by board implementation */
 void mpc8308_init(void);
 void mpc8308_set_fpga_reset(unsigned state);