gpio: sta2x11: Inline regs macro

I don't like the __namespace and this is simple enough to just
inline at all sites.

Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Acked-by: Alessandro Rubini <rubini@gnudd.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>