Format kernel-doc comments of the exported functions to follow the
typical format that does not have tab indentation. Also capitalize
parameter descriptions and add a missing period.

No functional changes intended.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>