media: atmel: atmel-isc-base: report frame sizes as full supported range

The ISC supports a full broad range of frame sizes.
Until now, the subdevice was queried for possible frame sizes and these
were reported to the user space.
However, the ISC should not care about which frame sizes the subdev
supports, as long as this frame size is supported.
Thus, report a continuous range from smallest frame size up to the max
resolution.

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>