video: mb862xx-i2c: local functions should not be exposed globally

Functions not referenced outside of a source file should be marked
static to prevent them from being exposed globally.

Quiets the sparse warnings:

warning: symbol 'mb862xx_i2c_stop' was not declared. Should it be static?
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

drivers/video/mb862xx/mb862xx-i2c.c

@@ -68,7 +68,7 @@ static int mb862xx_i2c_read_byte(struct i2c_adapter *adap, u8 *byte, int last)
 	return 1;
 }
 
-void mb862xx_i2c_stop(struct i2c_adapter *adap)
+static void mb862xx_i2c_stop(struct i2c_adapter *adap)
 {
 	struct mb862xxfb_par *par = adap->algo_data;