gpio: pca953x: use simple irqdomain

This switches the legacy irqdomain to the simple one, which will
auto-allocate descriptors, and also make sure that we use
irq_create_mapping() in the to_irq function. Also use the map function
of irq_domain_ops to setup the irq configuration on demand and no more
statically during the initialization of the driver.

Based on a initial patch from Linus Walleij <linus.walleij@linaro.org>

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
gpio: pca953x: use managed resources

Using the devm_* managed resources the pca driver can be simplified
and cut down on boilerplate code.

[gcl: fixed a inccorect reference to a removed label, "goto fail_out"
became "return ret"]

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>