Since JOYSTICK_SENSEHAT selects MFD_SIMPLE_MFD_I2C and the latter
depends on HAS_IOMEM, and since 'select' does not follow any
dependency chains, JOYSTICK_SENSEHAT should also depend on HAS_IOMEM
to prevent a kconfig warning and a build error:

WARNING: unmet direct dependencies detected for MFD_SIMPLE_MFD_I2C
  Depends on [n]: HAS_IOMEM [=n] && I2C [=y]
  Selected by [y]:
  - JOYSTICK_SENSEHAT [=y] && INPUT_JOYSTICK [=y] && INPUT [=y] && I2C [=y]

s390-linux-ld: drivers/mfd/simple-mfd-i2c.o: in function `simple_mfd_i2c_probe':
simple-mfd-i2c.c:(.text+0xc8): undefined reference to `devm_mfd_add_devices'

Fixes: 41657514 ("Input: add Raspberry Pi Sense HAT joystick driver")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220531022942.16340-1-rdunlap@infradead.orgSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>