soc: qcom: ipc_router_mhi_xprt: Avoid memory leak on read_data

Fix the memory leak issue by freeing the skb and packet
when the read fails or is the last normal empty read.

Change-Id: Ib23bb7ee253cd30b5d8b5b76d449b8b068d5fbba
Signed-off-by: Gustavo Solaira <gustavos@codeaurora.org>