misc: Add MPC83xx serdes driver

Add a driver to configure the SerDes (Serializer/Deserializer) lanes on
the MPC83xx architecture.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Mario Six <mario.six@gdsys.cc>

arch/powerpc/cpu/mpc83xx/serdes.c

@@ -8,6 +8,8 @@
  * Author: Li Yang <leoli@freescale.com>
  */
 
+#ifndef CONFIG_MPC83XX_SERDES
+
 #include <config.h>
 #include <common.h>
 #include <asm/io.h>
@@ -148,3 +150,5 @@ void fsl_setup_serdes(u32 offset, char proto, u32 rfcks, char vdd)
 	tmp |= FSL_SRDSRSTCTL_RST;
 	out_be32(regs + FSL_SRDSRSTCTL_OFFS, tmp);
 }
+
+#endif /* !CONFIG_MPC83XX_SERDES */