net/mlx5: E-Switch, Enable restore table only if reg_c1 is supported

Reg c0/c1 matching, rewrite of regs c0/c1, and copy header of regs c1,B
is needed for the restore table to function, might not be supported by
firmware, and creation of the restore table or the copy header will
fail.

Check reg_c1 loopback support, as firmware which supports this,
should have all of the above.

Fixes: 11b717d6

 ("net/mlx5: E-Switch, Get reg_c0 value on CQE")
Signed-off-by: Paul Blakey <paulb@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>