BugLink: http://bugs.launchpad.net/bugs/1770565

Program the 'iboost_bit' based on what the VBT says it should be for
the specific port type, rather than assume it's always the same
for DP and HDMI.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1468328376-6380-8-git-send-email-ville.syrjala@linux.intel.com

(cherry picked from commit 1edaaa2f)
Signed-off-by: Timo Aaltonen <timo.aaltonen@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>