regulator: fixed-helper: Add missing "Return" kerneldoc section

regulator: fixed-helper: Add missing "Return" kerneldoc section

kernel-doc complains about missing "Return" section for the function
regulator_register_always_on().

Add a "Return" section for it based on its behavior.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20240829085131.1361701-8-wenst@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>