First part of an extension to let the pca9539 driver support more chips,
starting with pca9534, pca9535, pca9536, pca9537, and pca9538.

This renames the files and modifies the Makefile.
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@pengutronix.de>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>