staging: lustre: fix bug with LL_MRF_RETURN in loop_make_request

Turns out that LL_MRF_RETURN is "void" so loop_make_request() would fall
through to the error path for a successful call.  Either this never
matters, or the error path really doesn't do anything.

Fix it up to do what the code is written to look like it is doing, if
that really is what it should be doing is another story...

Cc: Peng Tao <tao.peng@emc.com>
Cc: Zhao Hongjiang <zhaohongjiang@huawei.com>
Cc: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>