Add splitter configuration to crtc state, and read it where
supported. Also add splitter state dumping. The stream splitter will be
required for eDP MSO.

v4:
- Catch invalid splitter configuration (Uma)

v3:
- Convert segment timings to full panel timings.
- Refer to splitter instead of mso in crtc state.
- Dump splitter state.

v2: Add warning for mso being enabled on pipes other than A.

Cc: Nischal Varide <nischal.varide@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/95cbe1c9d45edf3e3ec252e49fb49055def98155.1614682842.git.jani.nikula@intel.com