Update user access region, UAR, APIs in the core in mlx5core.

This change include several changes as listed below all related to UAR.
UAR is a special PCI memory area where the so-called doorbell register and
blue flame register live. Blue flame is a feature for sending small packets
more efficiently via a PCI memory page, instead of using PCI DMA.

• All structures and functions named xxx_uuars were renamed into xxx_bfreg.
• Remove partially implemented Blueflame support from mlx5en(4) and mlx5ib.
• Implement blue flame register allocator.
• Use blue flame register allocator in mlx5ib.
• A common UAR page is now allocated by the core to support doorbell register writes for all of mlx5en and mlx5ib, instead of allocating one UAR per sendqueue.
• Add support for DEVX query UAR.
• Add support for 4K UAR for libmlx5.

Linux commits:
7c043e908a74ae0a935037cdd984d0cb89b2b970
2f5ff26478adaff5ed9b7ad4079d6a710b5f27e7
0b80c14f009758cefeed0edff4f9141957964211
30aa60b3bd12bd79b5324b7b595bd3446ab24b52
5fe9dec0d045437e48f112b8fa705197bd7bc3c0
0118717583cda6f4f36092853ad0345e8150b286
a6d51b68611e98f05042ada662aed5dbe3279c1e

MFC after: 1 week
Sponsored by: Mellanox Technologies // NVIDIA Networking