Bluetooth: hci_qca: use the power sequencer for wcn7850 and wcn6855

Bluetooth: hci_qca: use the power sequencer for wcn7850 and wcn6855

In preparation for using the power sequencing subsystem on sm8650 boards
and X13s laptop let's make pwrseq the default for wcn7850 and wcn6855.

Both these models require an enable GPIO so we can safely assume that if
the property is not there, then we should try to get the power
sequencer. Due to how the pwrseq lookup works - checking the provider at
run-time - we cannot really do it the other way around as we'd get stuck
forever on -EPROBE_DEFER.

If the relevant OF node does have the 'enable-gpios' property, we
fallback to the existing code for backward compatibility with older DTs.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>