arch/x86: Clean up mxt224 platform data

arch/x86: Clean up mxt224 platform data

BZ: 20624

Remove useless platform data functions for mxt224 touchcreen
driver. Let the driver take defaults one instead.

Remove valid_interrupt function since it is the exact same than
driver's default one.
Remove init_platform_hw and exit_platform_hw functions since
they are empty.

Change-Id: Iff0344ece9971903c0f72f960a5be8d25fcabf51
Signed-off-by: Gilles Rimauro <gilles.rimauro@intel.com>
Reviewed-on: http://android.intel.com:8080/32376
Reviewed-by: Kuppuswamy, Sathyanarayanan <sathyanarayanan.kuppuswamy@intel.com>
Reviewed-by: Du, Alek <alek.du@intel.com>
Reviewed-by: Gross, Mark <mark.gross@intel.com>
Tested-by: Wang, Zhifeng <zhifeng.wang@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>