Extend QP creation to get uar page index from user space, this mode can be
used with the UAR dynamic mode APIs to allocate/destroy a UAR object.

As part of enabling this option blocked the weird/un-supported cross
channel option which uses index 0 hard-coded.

This QP flag wasn't exposed to user space as part of any formal upstream
release, the dynamic option can allow having valid UAR page index instead.

Link: https://lore.kernel.org/r/20200324060143.1569116-4-leon@kernel.orgSigned-off-by: NYishai Hadas <yishaih@mellanox.com>
Reviewed-by: NMichael Guralnik <michaelgur@mellanox.com>
Signed-off-by: NLeon Romanovsky <leonro@mellanox.com>
Signed-off-by: NJason Gunthorpe <jgg@mellanox.com>