iio: adc: at91-sama5d2_adc: add startup and tracktim as parameter for at91_adc_setup_samp_freq()

Add startup and tracktim as parameter for at91_adc_setup_samp_freq()
function. In case of temperature sensor being enabled these parameters
will be configured on temperature read request to improve the accuracy
of the read temperature.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220803102855.2191070-15-claudiu.beznea@microchip.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>