i2c: made unused function i2c_mux_add_device static

and removed it from the .h file
Signed-off-by: NFrans Meulenbroeks <fransmeulenbroeks@gmail.com>

common/cmd_i2c.c

@@ -1357,7 +1357,7 @@ U_BOOT_CMD(
 );
 
 #if defined(CONFIG_I2C_MUX)
-int i2c_mux_add_device(I2C_MUX_DEVICE *dev)
+static int i2c_mux_add_device(I2C_MUX_DEVICE *dev)
 {
 	I2C_MUX_DEVICE	*devtmp = i2c_mux_devices;
 

include/i2c.h

@@ -127,8 +127,6 @@ typedef struct _mux_device {
 	struct _mux_device	*next;
 } I2C_MUX_DEVICE;
 
-int	i2c_mux_add_device(I2C_MUX_DEVICE *dev);
-
 I2C_MUX_DEVICE	*i2c_mux_search_device(int id);
 I2C_MUX_DEVICE *i2c_mux_ident_muxstring (uchar *buf);
 int i2x_mux_select_mux(int bus);