iio: adc: ad4130: zero-initialize clock init data

The clk_init_data struct does not have all its members
initialized, causing issues when trying to expose the internal
clock on the CLK pin.

Fix this by zero-initializing the clk_init_data struct.

Fixes: 62094060

 ("iio: adc: ad4130: add AD4130 driver")
Signed-off-by: Cosmin Tanislav <demonsingur@gmail.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240207132007.253768-1-demonsingur@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>