[patch] iio: inkern: fix a NULL dereference on error

[Dan Carpenter]

In twl4030_bci_probe() there are some failure paths where we call
iio_channel_release() with a NULL pointer.  (Apparently, that driver can
opperate without a valid channel pointer).  Let's fix it by adding a
NULL check in iio_channel_release().

Fixes: 2202e1fc5a29 ('drivers: power: twl4030_charger: fix link problems when 
building as module')
Signed-off-by: Dan Carpenter <dan.carpen...@oracle.com>

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 80fbbfd..734a004 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -349,6 +349,8 @@ EXPORT_SYMBOL_GPL(iio_channel_get);
 
 void iio_channel_release(struct iio_channel *channel)
 {
+       if (!channel)
+               return;
        iio_device_put(channel->indio_dev);
        kfree(channel);
 }