commit 3475c3d0 upstream.

Flush the FIFOs when the stream is prepared for use.  This avoids
an inadvertent swapping of the left/right channels if the FIFOs are
not empty at startup.
Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>