msm: mdss: enable tearcheck after panel on for synchronization

When pingpong split is enabled, we need to configure both PP0 and
PP4 tear check blocks for synchronization between the two interfaces.
In the existing implementation, the two tearcheck blocks are being
enabled at different time and the two TE counters are asynchronous.
This asynchronous behaviour could lead to DSI FIFO underflows and
are fatal during subsequent panel on/off. This change enables both
the tear check blocks together and waits for the TE signal  to
synchronize.

Change-Id: I966dcead59028c729a71cc7e47343303b0b9a6b2
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>