msm: ipc: Fix a false leak indication in IPC Router

KMEMLEAK scan reports a memory leak about an SKB allocated in
msm_ipc_router_sendmsg function. The concerned SKB is released by the
underlying transport abstraction layer when the data within the SKB is
successfully transmitted.

Avoid this false leak indication with a no-leak annotation.

CRs-Fixed: 530458
Change-Id: I21a6fa27d9bc1a5d99a607ccc8ed890c18417b10
Signed-off-by: Monu Surana <msurana@codeaurora.org>