Revert "USB: rndis: Honor dl_max_packet_size value sent by host"

This reverts commit 8d0058d8.

Instead, set GSI IN aggregation size by directly reading the
RNDIS_MSG_INIT message's MaxTransferSize field.

Change-Id: Ia36ac79f4fce2c3e89a542cfa82c39c4c1b52700
Signed-off-by: Jack Pham <jackp@codeaurora.org>