net: qualcomm: rmnet: Reuse port information when adding header

Pass in the port information from egress handler rather than
querying it again when stamping the MAP header.

CRs-fixed: 2448730
Change-Id: Icc4be9215c2ebdfe5054a8c46e47e50bd799afa0
Acked-by: Ning Cai <ncai@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>