radio tea5764, si4713: get rid of warning: no previous prototype

drivers/media/radio/radio-tea5764.c:148:5: warning: no previous prototype for 'tea5764_i2c_read' [-Wmissing-prototypes]
drivers/media/radio/radio-tea5764.c:168:5: warning: no previous prototype for 'tea5764_i2c_write' [-Wmissing-prototypes]
drivers/media/radio/si4713-i2c.c:1772:6: warning: no previous prototype for 'si4713_ioctl' [-Wmissing-prototypes]
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/radio/radio-tea5764.c

@@ -145,7 +145,7 @@ struct tea5764_device {
 };
 
 /* I2C code related */
-int tea5764_i2c_read(struct tea5764_device *radio)
+static int tea5764_i2c_read(struct tea5764_device *radio)
 {
 	int i;
 	u16 *p = (u16 *) &radio->regs;
@@ -165,7 +165,7 @@ int tea5764_i2c_read(struct tea5764_device *radio)
 	return 0;
 }
 
-int tea5764_i2c_write(struct tea5764_device *radio)
+static int tea5764_i2c_write(struct tea5764_device *radio)
 {
 	struct tea5764_write_regs wr;
 	struct tea5764_regs *r = &radio->regs;

drivers/media/radio/si4713-i2c.c

@@ -1769,7 +1769,7 @@ static int si4713_s_ctrl(struct v4l2_subdev *sd, struct v4l2_control *ctrl)
 }
 
 /* si4713_ioctl - deal with private ioctls (only rnl for now) */
-long si4713_ioctl(struct v4l2_subdev *sd, unsigned int cmd, void *arg)
+static long si4713_ioctl(struct v4l2_subdev *sd, unsigned int cmd, void *arg)
 {
 	struct si4713_device *sdev = to_si4713_device(sd);
 	struct si4713_rnl *rnl = arg;