sfxge(4): fix probes in licensing support

EFSYS_PROBE1 takes one typed value (in addition to the probe name),
whereas EFSYS_PROBE has just the probe name.

Which to use is determined by the probe name - "fail1" probes are
expected to include the function result.

Submitted by: Mark Spender <mspender at solarflare.com>
Sponsored by: Solarflare Communications, Inc.
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D18118