IB/ehca: Remove unnecessary memory operations for userspace queue pairs

The queue map for flush completion circumvention is only used for
kernel space queue pairs.  This patch skips the allocation of the
queue maps in case the QP is created for userspace.  In addition, this
patch does not iomap the galpas for kernel usage if the queue pair is
only used in userspace.  These changes will improve the performance of
creation of userspace queue pairs.

Signed-off-by: Stefan Roscher <stefan.roscher@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>