msm: mdss: set interface stopped flag properly during suspend

In current implementation while disabling interface, the
interface stopped flag is not keeping the correct value. This
is causing issues when later if we use this flag during command
autorefresh feature disable. So update the flag properly after
wiping out display context structure to store correct value.

Change-Id: Id2cc64e3f10711b92f8b8f4f36f73f716c9ac831
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>