net: rmnet_data: process MAP commands only after frame deaggregation

It is not guaranteed that MAP commands will be in their own frame. Some
commands may be embedded in a large aggregated frame of datagrams. This
patch forces MAP command processing to occur after the deaggregation
routing. This has the side-effect of incurring a malloc/memcpy latency
penalty for each MAP command. This also introduces a side-effect where
every packet after de-aggregation will need to be inspected for the
cmd bit.

Change-Id: Icc5ad1e7d622a35883f858c2c132c9679f43c79e
Signed-off-by: Harout Hedeshian <harouth@codeaurora.org>