drm/i915/icl: Define TRANS_DSI_FUNC_CONF register

This patch defines transcoder function configuration
registers and its bitfields for both DSI ports.
Used while programming/enabling DSI transcoder.

v2: Changes (Jani N)
    - Define _SHIFT and _MASK for bitfields
    - Define values for fields already shifted in place

v3 by Jani:
 - Fix _SHIFT fields copy-pasted from _MASK
 - Indentation fixes
 - Reduce S3D orientation to single macro
 - Wrap a macro parameter in parens

Signed-off-by: Madhav Chauhan <madhav.chauhan@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/f188d3e59f27cbcac87d331af3d0222249db7fe4.1539613303.git.jani.nikula@intel.com