cxgbe tom: Limit TOE connections to 2 reassembly islands always

Previously this was only limited on T6 cards to support switching from
ULP_MODE_NONE to ULP_MODE_TLS. To support switching to
ULP_MODE_TCPDDP, enable this for all adapters.

Reviewed by: np
Sponsored by: Chelsio Communications
Differential Revision: https://reviews.freebsd.org/D43669