ARM: ux500 enable the AB8500 gpio for all HREFs

The AB8500 GPIO was only registered for the pre-v60 HREF but should
be made available on all HREF variants, move the DT entry to the
common file.

Cc: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>