sound/soc/codecs/rt5645.c is the only user of the rt5645_platform_data,
move its definition to sound/soc/codecs/rt5645.c and remove the now
empty include/sound/rt5645.h file.

Note since the DMI quirk mechanism uses pointers to the
rt5645_platform_data struct we can NOT simply add its members to
the rt5645_priv struct and completely remove the struct.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210306230223.516566-1-hdegoede@redhat.comSigned-off-by: Mark Brown <broonie@kernel.org>