net/bonding: remove socket id check

Socket id parsed from the user was checked
if it was in the range of available sockets.
This check is unnecessary, as the socket specified
might not have memory anyway, so it will fail
at memory allocation.

Therefore, the best solution is to remove this check.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: Declan Doherty <declan.doherty@intel.com>