drm/i2c: Move ptn driver from auxdisplay to drm

drm/i2c: Move ptn driver from auxdisplay to drm

In order to properly synchronize setting up the ptn bridge chip with the
displayport drm driver, we need to move ptn into drm.

The original hope was to keep ptn completely seperate from drm, and have
it just act like a regular monitor. Unfortunately, the bridge is
designed such that it cannot be configured until after it asserts
hotplug. This creates a race between the DP driver detecting hotplug and
reading edid, and the ptn driver configuring its edid emulation setting.

By moving it into the drm subsystem, we can hold off reading edid until
the bridge is properly set up.

BUG=chrome-os-partner:11158
TEST=Tested on snow, no regressions detected.

Change-Id: I99f696b4eeabf36f3055c3772482013397da5002
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/36791
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>