Revert "iwlwifi: assign directly to iwl_trans->cfg in QuZ detection"

Revert "iwlwifi: assign directly to iwl_trans->cfg in QuZ detection"

This reverts commit 3ef2276d7a739aa3a3a71d7cd922b0c84424c680.

Both that commit and commit a53936f56b1daccf314db09dfc3693ed4a5f1c2d
attempted to fix the same bug (dead assignments to the local variable
cfg), but they did so in incompatible ways. When they were both merged,
independently of each other, the combination actually caused the bug to
reappear, leading to a firmware crash on boot for some cards.

https://bugzilla.kernel.org/show_bug.cgi?id=205719

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Acked-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>