intel_scu_mip: Add mip sysfs interface

intel_scu_mip: Add mip sysfs interface

BZ: 30963

This patch adds sysfs interface for intel_scu_mip driver, which can be
used for debugging and testing of mip read/write.

Change-Id: Iae052d7773f5a056feaecaabc3cfff4e47a301a6
Signed-off-by: Shijie Zhang <shijie.zhang@intel.com>
Reviewed-on: http://android.intel.com:8080/42863
Reviewed-by: Du, Alek <alek.du@intel.com>
Reviewed-by: Yang, Bin <bin.yang@intel.com>
Tested-by: Wang, Zhifeng <zhifeng.wang@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>