qlcnic: fix estimation of receive MSS in case of LRO for 83xx adapter

Set gso_size to MSS obtained from adapter to avoid incorrect estimation
of receive MSS, which would lead to delayed ACKs in some traffic patterns

Example:
Send two or three packets and wait for ack and only then send
remaining packets.

Signed-off-by: Shahed Shaikh <shahed.shaikh@qlogic.com>
Signed-off-by: Jitendra Kalsaria <jitendra.kalsaria@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>