iwlwifi: pcie: support secured boot flow for family 8000 B step

The driver loads the 2 CPU sections, then it needs to let
the firmware know to start the authentication of the
sections. This is done by writing the relevants bits to
FH_UCODE_LOAD_STATUS.

For CPU1, the driver sets the lower 16 bits. For both CPUs,
the driver sets all the 32 bits.

Signed-off-by: Eran Harary <eran.harary@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>