net: qualcomm: rmnet: Avoid copy twice in non linear cases

This avoids the linearization in the uplink aggregation path
when a non linear skb is received from stack.

CRs-fixed: 2485919
Change-Id: Id86e54494340cb3a7d40aa70620741d79078ad5f
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>