sfc: Do not retry hardware probe if it schedules a reset

If efx_pci_probe_main() schedules an INVISIBLE or ALL reset (but
nothing more drastic), we retry it up to 5 times.  So far as I'm
aware, this was a workaround for bugs in Falcon A0 which were fixed
in production silicon.  Remove the retry.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>