callout(9): add sbt flavors of callout_schedule

Differential Revision:	https://reviews.freebsd.org/D1161 (partial)
Reviewed by:	jhb, markj
MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275045 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
whitespace and cosmetic changes in callout_reset family of macros

- add parentheses around macro parameters for consistent style
- remove redundant parentheses around an expression
- use tab before a line continuation symbol

Differential Revision:	https://reviews.freebsd.org/D1161 (partial)
Reviewed by:	markj
MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275046 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f