device property: Sync descriptions of swnode array and group APIs

device property: Sync descriptions of swnode array and group APIs

After a few updates against swnode APIs the kernel documentation, i.e.
for swnode group registration and unregistration deviates from the one
for swnode array. In general, the same rules are applied to both.
Hence, synchronize descriptions of swnode array and group APIs

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210308103644.81960-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>