Increase time limit of test/mpi/rma/atomic_get test to 5 min.

This test occasionally run more than 3 min (default time limit)
on OFI platform. This patch increases the time limit to 5 min.
Signed-off-by: Pavan Balaji <balaji@anl.gov>

test/mpi/rma/testlist.in

@@ -131,7 +131,7 @@ at_complete 2
 atomic_rmw_fop 3
 atomic_rmw_cas 3
 atomic_rmw_gacc 3
-atomic_get 3 mpiversion=3.0
+atomic_get 3 mpiversion=3.0 timeLimit=300
 aint 2 mpiversion=3.1
 acc-pairtype 2
 manyget 2