ASoC: samsung: Remove tests of member address

The driver was checking for non-NULL address of struct's members:
 - s3c_audio_pdata->type (union),
 - s3c_audio_pdata->type.i2s (embedded struct).

This is pointless as these will be always non-NULL.  The 's3c_audio_pdata'
is always initialized in static memory so it will be zeroed.
Additionally the 'type' member was an union with only one member.

It is safe to reorganize the structures to get rid of useless union and
checks for addresses to fix the coccinelle warning:
	>> sound/soc/samsung/i2s.c:1270:2-4: ERROR: test of a variable/field address

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>