HV: hv_balloon: fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Cc: "K. Y. Srinivasan" <[email protected]>
Cc: Haiyang Zhang <[email protected]>
Cc: Wei Liu <[email protected]>
Cc: Dexuan Cui <[email protected]>
Fixes: d180e0a ("Drivers: hv: Create debugfs file with hyper-v balloon usage information")
Cc: stable <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/hv/hv_balloon.c

@@ -1963,7 +1963,7 @@ static void  hv_balloon_debugfs_init(struct hv_dynmem_device *b)
 
 static void  hv_balloon_debugfs_exit(struct hv_dynmem_device *b)
 {
-	debugfs_remove(debugfs_lookup("hv-balloon", NULL));
+	debugfs_lookup_and_remove("hv-balloon", NULL);
 }
 
 #else