LinuxKPI: add counted_by_le() and counted_by_be()
The former is needed by a wireless driver at v6.17.
Approved by:	re (cperciva)
Reviewed by:	dumbbell, emaste
Differential Revision: https://reviews.freebsd.org/D53203
(cherry picked from commit 0a4b11ddb298fa08e1a81af7337995a3769552bf)
(cherry picked from commit 0e30cab0f32ee40e89f59b3a287ae96c084e1e7a)