drivers: rmnet: Add option for wq context packets

Timer in perf module requires that packets be passed
to gro cells instead of regular GRO path since wq
context has no access to napi struct. This change
allows for clients of rmnet to designate what context
packets they are delivering to rmnet are coming from.

Change-Id: I24e1430d85494e5e04405fc3be901f68214022d5
Signed-off-by: Conner Huff <chuff@codeaurora.org>