msm: mdss: Add traffic shaper for rotator path

Rotator is a non real time client. Traffic shaper helps
spread out rotator bandwidth request so that this non
real-time client won't compete with other real time
read clients.

Change-Id: I07dbc0a6287e31d33084e27a8e1f3e9ea365d3ab
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>