FreeBSD/src 9312900 (r342003)share/man/man9 pwmbus.9 pwm.9, sys/conf files

Add a pwm subsystem so we can configure pwm controller from kernel and userland.

The pwm subsystem consist of API for PWM controllers, pwmbus to register them
and a pwm(8) utility to talk to them from userland.

Reviewed by:    oshgobo (capsicum), bcr (manpage), 0mp (manpage)
Differential Revision:  https://reviews.freebsd.org/D17938
DeltaFile
+244-0sys/dev/pwm/pwmbus.c
+218-0usr.sbin/pwm/pwm.c
+161-0sys/dev/pwm/pwmc.c
+111-0sys/dev/pwm/pwmbus_if.m
+109-0sys/dev/pwm/ofw_pwm.c
+106-0sys/dev/pwm/pwm_if.m
+98-0share/man/man9/pwmbus.9
+96-0usr.sbin/pwm/pwm.8
+93-0share/man/man9/pwm.9
+64-0sys/dev/pwm/pwmbus.h
+53-0sys/sys/pwm.h
+6-0usr.sbin/pwm/Makefile
+5-0sys/conf/files
+2-0share/man/man9/Makefile
+1-0usr.sbin/Makefile
+1,367-015 files

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