iwlwifi: pcie: implement Bz device startup

Device startup changed in Bz, some register bits moved around.
Change the code accordingly.

The new Bz hardware changes also the way we wake it (grab NIC
access) and the way we disable bus mastering, update the driver
code accordingly.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210802215208.00a137364a95.I059a2abac948965458862941ee7db6a2e1076fa6@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>