gpio: tegra: Fix irq_set_affinity

The irq_set_affinity callback should not be set if parent IRQ domain
doesn't present because gpio-tegra driver callback fails in this case,
causing a noisy error messages on system suspend:

 Disabling non-boot CPUs ...
 IRQ 26: no longer affine to CPU1
 IRQ128: set affinity failed(-22).
 IRQ130: set affinity failed(-22).
 IRQ131: set affinity failed(-22).
 IRQ 27: no longer affine to CPU2
 IRQ128: set affinity failed(-22).
 IRQ130: set affinity failed(-22).
 IRQ131: set affinity failed(-22).
 IRQ 28: no longer affine to CPU3
 IRQ128: set affinity failed(-22).
 IRQ130: set affinity failed(-22).
 IRQ131: set affinity failed(-22).
 Entering suspend state LP1

Hence just don't specify the irq_set_affinity callback if parent PMC
IRQ domain is missing. Tegra isn't capable of setting affinity per GPIO,
affinity could be set only per GPIO bank, thus there is nothing to do
for gpio-tegra in regards to CPU affinity without the parent IRQ domain.

Tested-by: Peter Geis <pgwipeout@gmail.com> # Ouya T30
Tested-by: Matt Merhar <mattmerhar@protonmail.com> # Ouya T30
Tested-by: Dmitry Osipenko <digetx@gmail.com> # A500 T20 and Nexus7 T30
Fixes: efcdca286eef ("gpio: tegra: Convert to gpio_irq_chip")
Reported-by: Matt Merhar <mattmerhar@protonmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>