soc: qcom: ipc_router_mhi_xprt: Increase the read timeout

Increase the timeout to deal with high system load
situation where the IPA draining can take a few hundred
milliseconds. This happens occasionally during stress
boot test.

Change-Id: I5cb7535b3669a2df688fa16876be605fd23d48d9
Signed-off-by: Gustavo Solaira <gustavos@codeaurora.org>