drm/i915/dg2: Don't wait for AUX power well enable ACKs

On DG2 we're supposed to just wait 600us after programming the well
before moving on; there won't be an ack from the hardware.

Bspec: 49296
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210721223043.834562-14-matthew.d.roper@intel.com