lib/string_helpers: Introduce parse_int_array_user()

lib/string_helpers: Introduce parse_int_array_user()

Add new helper function to allow for splitting specified user string
into a sequence of integers. Internally it makes use of get_options() so
the returned sequence contains the integers extracted plus an additional
element that begins the sequence and specifies the integers count.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20220904102840.862395-2-cezary.rojewski@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>