USB: rndis: Honor dl_max_packet_size value sent by host

This change starts using dl_max_packet_size value sent by host
as part of USB RNDIS init message communication. Using default
dl_max_packet_size value results into low throughput with more
data loss on host side as host side RNDIS can't support
de-aggregation (applicable for Linux Host RNDIS driver) or it
ignores received more data then host side RNDIS can handle. To
use fine tune dl_max_packet_size for better throughput, driver
selects minimum value between host supported dl_max_packet_size
and default size (i.e. 9216 bytes as RNDIS IN aggregation size).

Change-Id: I00c81bc905a032867c537536b01bf32584c37e63
Signed-off-by: Mayank Rana <mrana@codeaurora.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>