net/mlx5: Devcom, Rename paired to ready

In downstream patch devcom will provide support for more than two
devices. The term 'paired' will be renamed as 'ready' to convey a
more accurate meaning.

Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>