MLK-10092-2 dts: Rename compatible string from ov564x to ov5640

There are two version ov5640 driver,
one is written with v4l2 int-device architecture,
and the other is written with v4l2 subdev architecture.
Rename subdev ov5640 compatible string from ov5640x
to ov5640 to distinguish with ov5640 int-device driver.
so ov564x is used for int-device architecture and
ov5640 is used for subdev architecture.

Signed-off-by: Sandor Yu <R01008@freescale.com>