iw_cxgb4: detect fatal errors while creating listening filters

In c4iw_create_listen(), if we're using listen filters, then bail out
of the busy loop if the device becomes fatally dead

Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>