msm: mdss: update lineptr instantly in cmd mode panels w/autorefresh

The lineptr interrupt is expected to be triggered and have the
ability to be updated instantly  whenever the panel is fetching
data. Previously, enabling lineptr was tied to kickoff and disabling
to pp_done work. Add capability to change the lineptr value instantly,
when auto-refresh is enabled and avoid disabling lineptr during that time.
Once enabled, lineptr can only be disabled when 0 is written to the node
while auto-refresh is enabled.

Change-Id: I9a1a478c857efd988984a0efb0a2b6475030c7ec
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>