gpio: make memory-mapped drivers depend on HAS_IOMEM

This one is pretty obvious: on UM Linux compilation of things
like allmodconfig and allyesconfig will fail due to the
absence of IO memory. Simply make these drivers depend on
HAS_IOMEM, it has been implicitly assumed all the time, so
just make it explicit.

The generic MMIO library also assumes that IOMEM is present
so make also this depend on HAS_IOMEM.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/Kconfig

@@ -65,6 +65,7 @@ config GPIO_SYSFS
 	  exported to userspace; this can be useful when debugging.
 
 config GPIO_GENERIC
+	depends on HAS_IOMEM # Only for IOMEM drivers
 	tristate
 
 # put drivers in the right section, in alphabetical order
@@ -74,6 +75,7 @@ config GPIO_MAX730X
 	tristate
 
 menu "Memory mapped GPIO drivers"
+	depends on HAS_IOMEM
 
 config GPIO_74XX_MMIO
 	tristate "GPIO driver for 74xx-ICs with MMIO access"