chardev: set variable ret to -EBUSY before checking minor range overlap

When allocating dynamic major, the minor range overlap check
in __register_chrdev_region() will not fail, so actually
there is no real case to passing non negative error code to
caller. However, set variable ret to -EBUSY before checking
minor range overlap will avoid false-positive warning from
code analyzing tool(like Smatch) and also make the code more
easy to understand.
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Chengguang Xu <cgxu519@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/char_dev.c

@@ -98,7 +98,7 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 			   int minorct, const char *name)
 {
 	struct char_device_struct *cd, *curr, *prev = NULL;
-	int ret = -EBUSY;
+	int ret;
 	int i;
 
 	if (major >= CHRDEV_MAJOR_MAX) {
@@ -129,6 +129,7 @@ __register_chrdev_region(unsigned int major, unsigned int baseminor,
 		major = ret;
 	}
 
+	ret = -EBUSY;
 	i = major_to_index(major);
 	for (curr = chrdevs[i]; curr; prev = curr, curr = curr->next) {
 		if (curr->major < major)