net: rmnet: Add trace subsystem

Add a trace template function for rmnet and use it for
profiling.

Change-Id: I7ef86611d31a4b7ce464d53b3968cec5c799604d
Acked-by: Ning Cai <ncai@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>