gpio: add missing includes in machine.h

linux/types.h and linux/list.h should be included so the typed used in
the header file are always properly declared.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reported-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>