bnxt_re: Stop issuing further cmds to FW once a cmd times out

Once a cmd to FW times out(after 20s) it is reasonable to
assume the FW or atleast the control path is dead.
No point issuing further cmds to the FW as each subsequent cmd
with another 20s timeout will cascade resulting in unnecessary
traces and/or NMI Lockups.

Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>