regulator: Unify "negative error number" terminology in comments

regulator: Unify "negative error number" terminology in comments

Previous commits cleaning up kerneldoc used the term "negative error
number" to refer to error condition return values. Update remaining
instances of other terminology such as "error code" or "errno" as
well so the whole regulator subsystem is unified.

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/20240829085131.1361701-11-wenst@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>