[patch] [media] em28xx-i2c: rt_mutex_trylock() returns zero on failure

[Dan Carpenter]

The code is checking for negative returns but it should be checking for
zero.

Fixes: aab3125c43d8 ('[media] em28xx: add support for registering multiple i2c 
buses')
Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>
---
Is -EBUSY correct?  -EAGAIN?

diff --git a/drivers/media/usb/em28xx/em28xx-i2c.c 
b/drivers/media/usb/em28xx/em28xx-i2c.c
index a19b5c8..f80dd3a 100644
--- a/drivers/media/usb/em28xx/em28xx-i2c.c
+++ b/drivers/media/usb/em28xx/em28xx-i2c.c
@@ -507,9 +507,8 @@ static int em28xx_i2c_xfer(struct i2c_adapter *i2c_adap,
        if (dev->disconnected)
                return -ENODEV;
 
-       rc = rt_mutex_trylock(&dev->i2c_bus_lock);
-       if (rc < 0)
-               return rc;
+       if (!rt_mutex_trylock(&dev->i2c_bus_lock))
+               return -EBUSY;
 
        /* Switch I2C bus if needed */
        if (bus != dev->cur_i2c_bus &&