devlink: Add new "enable_roce" generic device param

New device parameter to enable/disable handling of RoCE traffic in the
device.

Signed-off-by: Michael Guralnik <michaelgur@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>