kernel/time/test_udelay.c: fix memory leak with using debugfs_lookup()

kernel/time/test_udelay.c: 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.

Link: https://lore.kernel.org/r/20230202151214.2306822-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>