RDMA/amso1100: Add spinlocks to serialize ib_post_send/ib_post_recv

The AMSO driver was not thread-safe in the post WR code and had
code that would sleep if the WR post FIFO was full. Since these
functions can be called on interrupt level I changed the sleep to a
udelay.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>