net: rmnet_data: Fix memory corruption in gro tracepoint

skb's passed to the network stack through napi_gro_receive can
be freed before it is used in the gro tracepoint to print the
ingress device.

Fix this by removing the skb as an argument. We could copy the
skb->dev to a string before passing it to napi_gro_receive and then
use it as an argument for the tracepoint but that would mean
unnecessary code in hotpath for debugging purposes.

Change-Id: I82055dbc9b84f405e8f63f7b2eeb7c80e5ae0c3a
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>