common/mlx5: glue UAR allocation

common/mlx5: glue UAR allocation

The isolated, protected and independent direct access to the HW by
multiple processes is implemented via User Access Region (UAR)
mechanism.
The UAR is part of PCI address space that is mapped for direct access to
the HW from the CPU.
UAR is comprised of multiple pages, each page containing registers that
control the HW operation.
UAR mechanism is used to post execution or control requests to the HW.
It is used by the HW to enforce protection and isolation between
different processes.

Add a glue command to allocate and free an UAR.

Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>