iwlwifi: mvm: fix init_dbg flow to work as expected

Even if running the driver with param init_dbg=1 - on INIT
image error - iwl_trans_stop_device() was still called. This
patch fixes that and calls iwl_trans_stop_device() on INIT
image failure only if init_dbg=0.

Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>