As we want gpio_chip .get() calls to be able to return negative
error codes and propagate to drivers, we need to go over all
drivers and make sure their return values are clamped to [0,1].
We do this by using the ret = !!(val) design pattern.

Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

  -- by advice of Arnd Bergmann
Signed-off-by: NGuan Xuetao <gxt@mprc.pku.edu.cn>
Reviewed-by: NArnd Bergmann <arnd@arndb.de>

This patch implements interrupts and gpio handling.
UniCore32 has 9 gpio interrupt sources.
And gpio device operations are also here.
Signed-off-by: NGuan Xuetao <gxt@mprc.pku.edu.cn>