msm: mdss: ensure rotator work is done before reconfiguring session

When queuing new parameters to rotator, need to ensure that current work
is done before reconfiguring pipe parameters, otherwise there may be a
mismatch on parameters with the buffers programmed once work is
scheduled.

Change-Id: I258aedca82bb10498d0ef4cbaa697a29c3c34a99
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>