pinctrl: single: Fix build when not built on ARM

Looks like we need a little bit of arch specific handling
with the generic IRQ. Fix the issue with an ifdef the
same way as other drivers do.

ARM needs things set to IRQF_VALID, which also then sets
noprobe. Others seem to use just irq_set_noprobe().

Otherwise we can get:

drivers/pinctrl/pinctrl-single.c: In function 'pcs_irqdomain_map':
drivers/pinctrl/pinctrl-single.c:1750:2: error: implicit declaration of function 'set_irq_flags' [-Werror=implicit-function-declaration]
drivers/pinctrl/pinctrl-single.c:1750:21: error: 'IRQF_VALID' undeclared (first use in this function)
drivers/pinctrl/pinctrl-single.c:1750:34: error: 'IRQF_PROBE' undeclared (first use in this function)

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>