RDMA/cxgb4: Validate the number of CQEs

Before create CQ, make sure that the requested number of CQEs is in the
supported range.

Fixes: cfdda9d7 ("RDMA/cxgb4: Add driver for Chelsio T4 RNIC")
Link: https://lore.kernel.org/r/20201108132007.67537-1-kamalheib1@gmail.com


Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>