drivers/pps: use surrounding "if PPS" to remove numerous dependency checks

Adding high-level "if PPS" makes lower-level dependency tests superfluous.

Link: http://lkml.kernel.org/r/alpine.LFD.2.20.1708261050500.8156@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>