drm/i915/dp: revert back to max link rate and lane count on eDP

Commit 7769db58 ("drm/i915/dp: optimize eDP 1.4+ link config fast
and narrow") started to optize the eDP 1.4+ link config, both per spec
and as preparation for display stream compression support.

Sadly, we again face panels that flat out fail with parameters they
claim to support. Revert, and go back to the drawing board.

v2: Actually revert to max params instead of just wide-and-slow.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109959


Fixes: 7769db58 ("drm/i915/dp: optimize eDP 1.4+ link config fast and narrow")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Matt Atwood <matthew.s.atwood@intel.com>
Cc: "Lee, Shawn C" <shawn.c.lee@intel.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v5.0+
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Tested-by: Albert Astals Cid <aacid@kde.org> # v5.0 backport
Tested-by: Emanuele Panigati <ilpanich@gmail.com> # v5.0 backport
Tested-by: Matteo Iervasi <matteoiervasi@gmail.com> # v5.0 backport
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190405075220.9815-1-jani.nikula@intel.com