iwlwifi: pcie: move power gating workaround earlier in the flow

We need to reset the NIC after setting the bits to enable power
gating and that cannot be done too late in the flow otherwise it
cleans other registers and things that were already configured,
causing initialization to fail.

In order to fix this, move the function to the common code in trans.c
so it can be called directly from there at an earlier point, just
after the reset we already do during initialization.

Fixes: 9a47cb98 ("iwlwifi: pcie: add workaround for power gating in integrated 22000")
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=205719


Cc: stable@ver.kernel.org # 5.4+
Reported-by: Anders Kaseorg <andersk@mit.edu>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>