Sqwerty: do full FIMD configuration

We were missing the configuration to bypass the image enhancement units,
and to set up the pins correctly.

This was previously being done by CoAsia uboot.
Without this, no image appears over VGA output.
Sqwerty: poll for VGA connection

At least for now, lets poll the DDC every 10 seconds to figure out
if the VGA display is present.

This requires the call to drm_kms_helper_poll_init() to be moved
later because it must be run when the connector is already created,
otherwise it will never start the poll loop.