orangefs: Axe some dead code

The "perf_counter_reset" case has already been handled above.
Moreover "ORANGEFS_PARAM_REQUEST_OP_READAHEAD_COUNT_SIZE" is not a really
consistent.
It is likely that this (dead) code is a cut and paste left over.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Martin Brandenburg <martin@omnibond.com>
Signed-off-by: Mike Marshall <hubcap@omnibond.com>