gpio: pl061: lock IRQs when starting them

This uses the new API for tagging GPIO lines as in use by
IRQs. This enforces a few semantic checks on how the underlying
GPIO line is used.

Cc: Haojian Zhuang <haojian.zhuang@linaro.org>
Cc: Deepak Sikri <deepak.sikri@st.com>
Acked-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>