leds: cpcap: new driver

Motorola CPCAP is a PMIC (power management integrated circuit) found
in multiple smartphones. This driver adds support for the chip's LED
controllers. This introduces support for all controllers used by the
Droid 4. According to Motorola's driver (no datasheets available)
there a couple of more LED controllers. I did not add support for
them, since I cannot verify that they work with my modifications.

Signed-off-by: Sebastian Reichel <sre@kernel.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>