mpc8308: Migrate system io config to Kconfig

Migrate the system IO configuration setting to Kconfig.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/arch/powerpc/cpu/mpc83xx/sysio/Kconfig b/arch/powerpc/cpu/mpc83xx/sysio/Kconfig
new file mode 100644
index 0000000..9e1f158
--- /dev/null
+++ b/arch/powerpc/cpu/mpc83xx/sysio/Kconfig
@@ -0,0 +1,7 @@
+menu "System I/O configuration"
+
+if ARCH_MPC8308
+source "arch/powerpc/cpu/mpc83xx/sysio/Kconfig.mpc8308"
+endif
+
+endmenu