powerpc/85xx: Add is_serdes_configured() support for MPC8568 SERDES

Add the ability to determine if a given IP block connected on SERDES is
configured.  This is useful for things like PCIe and SRIO since they are
only ever connected on SERDES.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/cpu/mpc85xx/Makefile b/arch/powerpc/cpu/mpc85xx/Makefile
index e1320bf..3c75429 100644
--- a/arch/powerpc/cpu/mpc85xx/Makefile
+++ b/arch/powerpc/cpu/mpc85xx/Makefile
@@ -79,6 +79,7 @@
 # SoC specific SERDES support
 COBJS-$(CONFIG_MPC8536) += mpc8536_serdes.o
 COBJS-$(CONFIG_MPC8548) += mpc8548_serdes.o
+COBJS-$(CONFIG_MPC8568) += mpc8568_serdes.o
 COBJS-$(CONFIG_MPC8572) += mpc8572_serdes.o
 COBJS-$(CONFIG_P1013)	+= p1013_serdes.o
 COBJS-$(CONFIG_P1022)	+= p1022_serdes.o