pinctrl: nsp: Set irq handler based on trig type

pinctrl: nsp: Set irq handler based on trig type

Rather than always using handle_simple_irq() as the gpio_irq_chip
handler, set a more appropriate handler based on the IRQ trigger type
requested. This is important for level triggered interrupts which need
to be masked during handling. Also, fix the interrupt acknowledge so
that it clears only one interrupt instead of all interrupts which are
currently active. Finally there is no need to clear the interrupt during
the interrupt handler, since the edge-triggered handler will do that for
us.

Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Reviewed-by: Ray Jui <ray.jui@broadcom.com>
Link: https://lore.kernel.org/r/20200703011830.15655-1-mark.tomlinson@alliedtelesis.co.nz
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>