drm/i915/dg1: Update voltage swing tables for DP

DG1's vswing tables are the same for eDP and HDMI but have slight
differences from ICL/TGL for DP.

v2:
 - Use a "_hbr2_hbr3" suffix on the table name to make it more clear
   that the same table is used for both HBR2 and HBR3 link rates.
   (Swathi)

Bspec: 49291
Cc: Clinton Taylor <Clinton.A.Taylor@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Cc: Swathi Dhanavanthri <swathi.dhanavanthri@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210108222528.1954514-1-matthew.d.roper@intel.com
Reviewed-by: Clint Taylor <Clinton.A.Taylor@intel.com>