linuxkpi: Add kmap_local_page_prot() and kunmap_local()

They are synonymous to kmap_atomic_prot() and kunmap_atomic()
respectively.

While here, fix several style(9) issues.

Reviewed by: manu
Approved by: manu
Differential Revision: https://reviews.freebsd.org/D38155

(cherry picked from commit 9dafbd0c69a6aade69b23a649548b6c7133f1091)