pinctrl: amd: fix __iomem annotation in amd_gpio_irq_handler()

pinctrl: amd: fix __iomem annotation in amd_gpio_irq_handler()

The regs pointer in amd_gpio_irq_handler() should have __iomem
on it, so add that to fix the following sparse warnings:

drivers/pinctrl/pinctrl-amd.c:555:14: warning: incorrect type in assignment (different address spaces)
drivers/pinctrl/pinctrl-amd.c:555:14:    expected unsigned int [usertype] *regs
drivers/pinctrl/pinctrl-amd.c:555:14:    got void [noderef] <asn:2> *base
drivers/pinctrl/pinctrl-amd.c:563:34: warning: incorrect type in argument 1 (different address spaces)
drivers/pinctrl/pinctrl-amd.c:563:34:    expected void const volatile [noderef] <asn:2> *addr
drivers/pinctrl/pinctrl-amd.c:563:34:    got unsigned int [usertype] *
drivers/pinctrl/pinctrl-amd.c:580:34: warning: incorrect type in argument 1 (different address spaces)
drivers/pinctrl/pinctrl-amd.c:580:34:    expected void const volatile [noderef] <asn:2> *addr
drivers/pinctrl/pinctrl-amd.c:580:34:    got unsigned int [usertype] *
drivers/pinctrl/pinctrl-amd.c:587:25: warning: incorrect type in argument 2 (different address spaces)
drivers/pinctrl/pinctrl-amd.c:587:25:    expected void volatile [noderef] <asn:2> *addr
drivers/pinctrl/pinctrl-amd.c:587:25:    got unsigned int [usertype] *

Signed-off-by: Ben Dooks (Codethink) <ben.dooks@codethink.co.uk>
Link: https://lore.kernel.org/r/20191022151154.5986-1-ben.dooks@codethink.co.uk
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>