usb: f_gsi: Set RNDIS DL aggr size based on host DL buffer size

Windows and Linux RNDIS hosts send a different DL buffer size
during enumeration in the REMOTE_NDIS_INITIALIZE_MSG. Add
support to select the DL aggregation size for IPA to be the
minimum of a new module param defined for RNDIS DL aggr size
and the value sent by the host. For RNDIS, trigger connect
with IPA from the handler for the OID_GEN_CURRENT_PACKET_FILTER
instead of SET_ALT as the REMOTE_NDIS_INITIALIZE_MSG arrives
after SET_ALT.

CRs-Fixed: 990354
Change-Id: Ib013baad00dfbcdd06e2ba75b656c31d7b80e462
Signed-off-by: Devdutt Patnaik <dpatnaik@codeaurora.org>