iio: adc: meson: init internal continuous ring counter

Disable internal continuous ring counter at init stage. Disable value
depends on SoC family: gxl and later SoCs write 1, others write 0.
This bit are inited in vendor boot code (bl2, bl33) already so do it
in the driver to not depend on other code.

Signed-off-by: George Stark <gnstark@sberdevices.ru>
Link: https://lore.kernel.org/r/20230715110654.6035-3-gnstark@sberdevices.ru
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>