Retire fence for frames are signaled based on vsync. Use the HW
vsync timestamp counter to calculate the precise vsync timestamp
and update the retire fence signal timestamp. This will offset
all IRQ and SW delays and sends the precise timestamp. Avoid
calculating the timestamp on error or panel dead events and
set the current ktime for those cases.
Change-Id: Ic762f7cd6daead9c8fdcb0f8aad6386cf980407d
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>