drivers: rmnet: shs: New dl marker v2 callbacks

New API's for main rmnet driver to call when handling
DL markers accompanied with v2 format. This allows
rmnet modules to receive new qcmd field upon callback.

Change-Id: I77637c77715342b1c2e685cde82f29b87b048cc6
Signed-off-by: Conner Huff <chuff@codeaurora.org>