RDMA/efa: Support QP with unsolicited write w/ imm. receive

Add a new EFA flags attribute for QP creation, and support unsolicited
write with immediate flag. QPs created with this flag set will not
consume receive work requests for incoming RDMA write with immediate.
Expose device capability bit for this feature support.

Reviewed-by: Daniel Kranzdorf <dkkranzd@amazon.com>
Reviewed-by: Firas Jahjah <firasj@amazon.com>
Signed-off-by: Michael Margolin <mrgolin@amazon.com>
Link: https://lore.kernel.org/r/20240506151829.6475-1-mrgolin@amazon.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>