msm: mdss: rotator: switch context between active-only and active+sleep

Modify the rotator bw vote to go to Active-Only in early stages when bw
is not needed, update the vote to Active+Sleep when bw must be
guaranteed.

Change-Id: I6a808831718426d93700fdf0c61b1eec1c0b2c1f
Signed-off-by: Terence Hampson <thampson@codeaurora.org>