Staging: most: cdev: Remove useless check

The variable mbo is already NULL tested so, check on it should be
removed.
Semantic patch used:

@@ expression E;
statement S; @@
if(E==NULL) {... return ...;}
- if(E)
  S
Signed-off-by: Shivani Bhardwaj <shivanib134@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/aim-cdev/cdev.c

@@ -208,7 +208,6 @@ static ssize_t aim_write(struct file *filp, const char __user *buf,
 	}
 	return actual_len - retval;
 error:
-	if (mbo)
 	most_put_mbo(mbo);
 	return err;
 }