media: atmel: atmel-isc-base: remove frameintervals VIDIOC

VIDIOC_ENUM_FRAMEINTERVALS is not recommended for a top video driver.
The frame rate is defined by the sensor subdevice, thus it can be queried
directly by anyone interested in the frame intervals.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>