QCA6390 can albo be used on non-DT systems so we must not make the power
sequencing the only option. Check if the serdev device consumes an OF
node. If so: honor the new contract as per the DT bindings. If not: fall
back to the previous behavior by falling through to the existing
default label.

Fixes: 9a15ce68 ("Bluetooth: qca: use the power sequencer for QCA6390")
Reported-by: Wren Turkal <wt@penguintechs.org>
Closes: https://lore.kernel.org/linux-bluetooth/27e6a6c5-fb63-4219-be0b-eefa2c116e06@penguintechs.org/Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>