net: rmnet_data: Add support for ftrace events

Adding initial support for ftrace events in order to help with
profiling and debugging. This initial set of events covers the
ingress and egress handlers.

Change-Id: I296d6fb9d009d8fdc2061e17d25e1275ee0a8a12
Signed-off-by: Harout Hedeshian <harouth@codeaurora.org>