pinctrl: at91-pio4: Make PINCTRL_AT91PIO4 depend on HAS_IOMEM to fix build error

If CONFIG_HAS_IOMEM is not set, devm_platform_ioremap_resource() will
be not built in drivers/base/platform.c and then there exists a build
error about undefined reference to "devm_platform_ioremap_resource"
in pinctrl-at91-pio4.c under COMPILE_TEST and CONFIG_PINCTRL_AT91PIO4,
make PINCTRL_AT91PIO4 depend on HAS_IOMEM to fix it.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Link: https://lore.kernel.org/r/1606209423-4742-1-git-send-email-yangtiezhu@loongson.cnSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/Kconfig

@@ -82,6 +82,7 @@ config PINCTRL_AT91
 config PINCTRL_AT91PIO4
 	bool "AT91 PIO4 pinctrl driver"
 	depends on OF
+	depends on HAS_IOMEM
 	depends on ARCH_AT91 || COMPILE_TEST
 	select PINMUX
 	select GENERIC_PINCONF