pinctrl: imx/mxs: move freescale drivers to subdir

This moves all the Freescale-related drivers (i.MX and MXS) to
its own subdirectory to clear the view.

Cc: Alexander Shiyan <shc_work@mail.ru>
Cc: Anson Huang <b20788@freescale.com>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Denis Carikli <denis@eukrea.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>