msm: sde: add hw timestamp support

Hw timestamp is part of version 5 sde rotator support. Add selection
logic to use either sw timestamp or hw timestamp based on hw version
probing.

Change-Id: Iae1396f32c8370eeeb0bd469281b641a21547b8a
Signed-off-by: Benjamin Chan <bkchan@codeaurora.org>