drivers/pps: aesthetic tweaks to PPS-related content

Collection of aesthetic adjustments to various PPS-related files,
directories and Documentation, some quite minor just for the sake of
consistency, including:

 * Updated example of pps device tree node (courtesy Rodolfo G.)
 * "PPS-API" -> "PPS API"
 * "pps_source_info_s" -> "pps_source_info"
 * "ktimer driver" -> "pps-ktimer driver"
 * "ppstest /dev/pps0" -> "ppstest /dev/pps1" to match example
 * Add missing PPS-related entries to MAINTAINERS file
 * Other trivialities

Link: http://lkml.kernel.org/r/alpine.LFD.2.20.1708261048220.8106@localhost.localdomain


Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Acked-by: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>