sdm: hwc: SetRefreshRate before validate IOCTL

- Refresh rate change needs to be followed by a commit, hence
  move setting the refresh rate to the draw thread.
- Validate has to be called on the new fps set, so introduce
  Preprepare to collect the refresh rates from metadata or idle
  fallback or force methods which can be set before validate
- Disable IdleTimer on fallback and restart it on commit which
  simplifies handling of idlefallback

Change-Id: Ifb8de6d53717a0b78ac642299aec30eb8a659479
Crs-fixed: 905211
11 files changed