soundwire: mipi-disco: fix clock stop modes

Fix support for clock_stop_mode0 and 1. The existing code uses a
bitmask between enums, one of which being zero. Or-ing with zero is
not very useful in general...Fix by or-ing with a BIT dependent on the
enum value.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>