media: ov6650: Drop obsolete .pclk_limit attribute

That attribute used to be obtained from platform data by a soc_camera
host interface and passed to the sensor driver for .s_mbus_fmt() video
operation callback, later reused as .set_fmt() pad operation callback,
to be able to limit frame rate.  The driver stored that value in its
private structure for further use from .g/s_parm(), later converted to
g/s_frame_interval().

On conversion of the driver from soc_camera sensor to a standalone V4L2
subdevice by commit 23a52386 ("media: ov6650: convert to standalone
v4l2 subdevice"), that attribute had been replaced by a constant and
hardcoded to an arbitrarily chosen pixel clock limit.  Drop it.  Host
interfaces can limit frame rate if needed by calling
.s_frame_interval().

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>