drm/kmb: Mipi DSI part of the display driver

Initializes Mipi DSI and sets up connects to ADV bridge

v2: removed license text
    upclassed dev_private, removed HAVE_IRQ. (Sam)

v3: Squashed all 59 commits to one

v4: review changes from Sam Ravnborg
	renamed dev_p to kmb

v5: corrected spellings
v6: corrected checkpatch warnings
v7: review changes Sam Ravnborg and Thomas Zimmerman
	removed unnecessary logs and defines and ifdef codes (Sam)
	split dphy_init_sequence smaller (Sam)
	removed redundant checks in kmb_dsi (Sam)
	changed kmb_dsi_init to drm_bridge_connector_init and
	drm_connector_attach_encoder to bridge's connector (Sam)
v8: call drm_bridge_attach with DRM_BRIDGE_ATTACH_NO_CONNECTOR
v9: renamed kmb_dsi_hw_init to kmb_dsi_mode_set (Daniel V)
v10: changes in driver to accommodate changes in DT to separate DSI
     entries (Sam R)
     added comments to clarify empty dsi host functions
     review changes from Sam to separate out DSI part,
     removed dependencies on drm side (Sam R)
v11: review changes for separate msscam node (Sam R, Neil A)
v12: fixed warnings Reported-by: kernel test robot <lkp@intel.com>

Signed-off-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1604538931-26726-7-git-send-email-anitha.chrisanthus@intel.com