msm: mhi_dev: Wake up the client on channel disconnect

In certain cases clients are blocked on read or poll once
the channel disconnect is received. During poll cases return
client with POLLHUP error. For the read case when client
is blocked on read wake up the thread.

Change-Id: Ideded84420b4995251773110ec083a80f9a3a76e
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>