soundwire: Kconfig: fix help format

[ Upstream commit 9d7cd9d500826a14fc68fb6994db375432866c6a ]

Move to the regular help format, --help-- is no longer recommended.

Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>