ASoC: Cyclic dependency between soc.h and soc-dapm.h

[Lars-Peter Clausen <lars@metafoo.de>]

The commit "ASoC: Decouple DAPM from CODECs" introduced a cyclic dependency between
soc.h and soc-dapm.h which leads to the following compile error, if a driver includes
soc-dapm.h without having included soc.h before:

	In file included from include/sound/soc-dapm.h:19,
	                 from sound/soc/codecs/jz4740.c:25:
	include/sound/soc.h:484: error: field 'dapm' has incomplete type

If soc.h has been included before the error does not happen, but then soc-dapm.h
already got included trough soc.h, so the driver does not really have to include it
again.
So I wonder if soc-dapm.h should be made completely internal and not be included
anywhere else but soc.h anymore?
Or if the cyclic dependency should be broken somehow, maybe by introducing a third
header file?

- Lars