drm/i915/glk: Add MIPIIO Enable/disable sequence

v2: Addressed Jani's Review comments(renamed bit field macros)
v3: Jani's Review comment for aligning code to platforms and added
wrapper functions.
v4: Corrected enable/disable seuqence as per BSPEC
v5: Corrected waiting twice for same bit (Review comments: Jani)
v6: Rebased to Han's patches(dsi restructuring code)

Signed-off-by: Deepak M <m.deepak@intel.com>
Signed-off-by: Madhav Chauhan <madhav.chauhan@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1488352893-29916-2-git-send-email-madhav.chauhan@intel.com