drm/i915: Add support for Generic MIPI panel driver

drm/i915: Add support for Generic MIPI panel driver

This driver makes use of the generic panel information from the VBT.
Panel information is classified into two - panel configuration and panel
power sequence which is unique to each panel. The generic driver uses the
panel configuration and sequence parsed from VBT block #52 and #53

v2: Address review comments by Jani
    - Move all of the things in driver c file from header
    - Make all functions static
    - Make use of video/mipi_display.c instead of redefining
    - Null checks during sequence execution

v3: Address review comments by Damien
    - Rename the panel driver file as intel_dsi_panel_vbt.c
    - Fix style changes as suggested
    - Correct comments for lp->hs and hs->lp count calculations
    - General updating comments to have more clarity
    - using max() instead of ternary operator
    - Fix names (ui_num, ui_den) while using UI in calculations
    - compute max of lp_to_hs switch and hs_to_lp switch while computing
      hs_lp_switch_count

Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>