msm: mdss: keep tear check enabled in LP1 power state

Prevent driver from disabling the tear check when
going to LP1 state. This is needed for certain
panels in cases where there are more than one
frame update in LP1 state.

Change-Id: Ib80f06e0609d9d49584118504adf87da44455563
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>