gpio: Add TC35892 GPIO driver

Add a GPIO driver to support the GPIOs on the TC35892 I/O Expander.

Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>