devlink: Add new "io_eq_size" generic device param

Add new device generic parameter to determine the size of the
I/O completion EQs.

For example, to reduce I/O EQ size to 64, execute:
$ devlink dev param set pci/0000:06:00.0 \
              name io_eq_size value 64 cmode driverinit
$ devlink dev reload pci/0000:06:00.0

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>