Add regulators, GPIOs and changes required to power on/off wcn6855.
Add support for firmware download for wcn6855 which is in the
linux-firmware repository as hpbtfw21.tlv and hpnv21.bin.

Based on the assumption that this is similar to the wcn6750

Tested-on: BTFW.HSP.2.1.0-00538-VER_PATCHZ-1
Signed-off-by: Steev Klimaszewski <steev@kali.org>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Tested-by: Bjorn Andersson <andersson@kernel.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>