iio: adc: at91-sama5d2_adc: initialize hardware after clock is started

The hw_init hardware init call must happen after the clock is prepared and
enabled. Otherwise, writing to the registers might lead to a block or
external abort.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Link: https://lore.kernel.org/r/20210901123013.329792-3-eugen.hristev@microchip.com


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