drm/amd/display: assign correct enum for edp revision

There are 2 edp enum revisions, no idea why, drop one, and just
assign 1.1 to the default value.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>