msm: mdss: Update slave controller dfps at the same time

Update the dynamic fps configuration of the slave dsi controller
while updating the master controller itself. This fixes corruption issues
for dual dsi panels that have dynamic fps feature enabled.

Change-Id: Ibf4f49dcf7a228be839c511bae14e66d60340070
Signed-off-by: Siddhartha Agrawal <agrawals@codeaurora.org>