gpiolib: Add the support for the msi parent domain

If the gpio's parent irqdomain is a msi irqdomain, we should ignore
the EEXIST error returned by the msi irqdomain because all the msi
interrupts have already been allocated.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Link: https://lore.kernel.org/r/20200114082821.14015-4-haokexin@gmail.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>