IB/iser: Remove atomic counter for posted receive buffers

Now that both the posting and reaping of receive buffers is done in
the completion path, the counter of outstanding buffers not be atomic.

Signed-off-by: Or Gerlitz <ogerlitz@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --cc drivers/infiniband/ulp/iser/iscsi_iser.h
Simple merge

diff --cc drivers/infiniband/ulp/iser/iser_initiator.c
Simple merge

diff --cc drivers/infiniband/ulp/iser/iser_verbs.c
Simple merge