ARM: dts: msm: Configure "qcom,sync-dly" to 800us for SDM660

Leaving LED_SYNC_DLY register to a default value of 200us
leads to OVP interrupts randomly during the brightness change.
The legacy driver configured this to 800us which does not exhibit
the OVP behavior.. Hence, configure the sync delay value
to 800us.

Change-Id: I84407a325dbcb51f77d53c6499f10df2f1b27d2a