mach-ux500: move MOP500 pins to separate file

Split off pin definitions for the MOP500 board family to its
own file.

Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>