RDMA/erdma: Add event queue implementation

Event queue (EQ) is the main notification way from erdma hardware to its
driver. Each erdma device contains 2 kinds EQs: asynchronous EQ (AEQ) and
completion EQ (CEQ). Per device has 1 AEQ, which used for RDMA async event
report, and max to 32 CEQs (numbered for CEQ0 to CEQ31). CEQ0 is used for
cmdq completion event report, and the rest CEQs are used for RDMA
completion event report.

Link: https://lore.kernel.org/r/20220727014927.76564-6-chengyou@linux.alibaba.com


Signed-off-by: Cheng Xu <chengyou@linux.alibaba.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>