CVE-2024-26711 iio: adc: ad4130: zero-initialize clock init data

In the Linux kernel, the following vulnerability has been resolved:

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.