iwlwifi: pcie: reset the NIC before the bring up

This allows to clean all kinds of bad state it might be in.
This solves situation where HW RFkill was switched while
the NIC was offline.
Until now, we relied on the firmware to do clean the
interrupt, but new firmwares don't do that any more.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>