mlxsw: spectrum_router: Track FIB entry committed state and skip uncommitted on delete

In case bulking is used, the entry that was previously added may not
be yet committed to the HW as it waits in the queue for bulk send. For
such entries, skip the deletion.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>