msk: Disable MSI by default.

For certain chips, enabling it will cause watchdog timeout and the chip
may not be able to work again w/o rebooting.

Reported-by: ferz
Remove /usr/pkg/xorg/... and /usr/X11R6/... from various paths/manpages.
installer: Remove pnpinfo configuration option.

pnpinfo(8) is i386 only. Also, it's easy enough to review it by logging
in as root.

Suggested-by: ftigeot
setkey(8): Use '#!/usr/bin/env' to find perl in a script.