ARM: dts: msm: Change vendor prefix to ovti for OV5648

Now 8926 and 8x26 shares the same driver of OV5648,
the vendor prefix has changed in sensor driver code.
Change vendor perfix to unblock 8x26 qrd front sensor.

Change-Id: I107dd68d98ffc12c3f71a1dc61a904181f2a75d5
Signed-off-by: Su Liu <suliu@codeaurora.org>