msm: mdss: disable programmable fetch when not in use

During the resolution switch use case where the active resolution
needs prefetch but the new resolution doesnot require it, currently
programmable fetch blocks are not disabled if not in use.

Change-Id: Ib5ea8ef75308132f5530aaf35aaea53858ea94a2
Signed-off-by: Raviteja Tamatam <travitej@codeaurora.org>