skb: Adding trace event for gso

This patch adds trace events to help with debug for gso feature
by identifying the packets (and their lengths) that are using
the segmentation offload feature.

CRs-Fixed: 2333588
Change-Id: Ibfe1194cc63e74c75047040b0c540713d539992e
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>