prov/verbs: Return -FI_ENOMEM if fi_allocinfo fails

Return a negative value, rather than positive value from
fi_ibv_getpeinfo.

Problem reported by: Reese Faucette <rfaucett@cisco.com>

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Merge pull request #168 from shefty/master

prov/verbs: Return -FI_ENOMEM if fi_allocinfo fails