I2C: adding new "i2c bus" Command to the I2C Subsystem.

With this Command it is possible to add new I2C Busses,
which are behind 1 .. n I2C Muxes. Details see README.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/cpu/mpc8260/i2c.c b/cpu/mpc8260/i2c.c
index 335177f..a96fbf8 100644
--- a/cpu/mpc8260/i2c.c
+++ b/cpu/mpc8260/i2c.c
@@ -780,10 +780,23 @@
 
 int i2c_set_bus_num(unsigned int bus)
 {
+#if defined(CONFIG_I2C_MUX)
+	if (bus < CFG_MAX_I2C_BUS) {
+		i2c_bus_num = bus;
+	} else {
+		int	ret;
+
+		ret = i2x_mux_select_mux(bus);
+		if (ret == 0)
+			i2c_bus_num = bus;
+		else
+			return ret;
+	}
+#else
 	if (bus >= CFG_MAX_I2C_BUS)
 		return -1;
 	i2c_bus_num = bus;
-
+#endif
 	return 0;
 }
 /* TODO: add 100/400k switching */