iio: adc: nxp-sar-adc: Avoid division by zero

iio: adc: nxp-sar-adc: Avoid division by zero

When Common Clock Framework is disabled, clk_get_rate() returns 0.
This is used as part of the divisor to perform nanosecond delays
with help of ndelay(). When the above condition occurs the compiler,
due to unspecified behaviour, is free to do what it wants to. Here
it saturates the value, which is logical from mathematics point of
view. However, the ndelay() implementation has set a reasonable
upper threshold and refuses to provide anything for such a long
delay. That's why code may not be linked under these circumstances.

To solve the issue, provide a wrapper that calls ndelay() when
the value is known not to be zero.

Fixes: 4434072a893e ("iio: adc: Add the NXP SAR ADC support for the s32g2/3 platforms")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202603311958.ly6uROit-lkp@intel.com/
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>