ASoC: simple-card-utils: care no Platform for DPCM

ASoC: simple-card-utils: care no Platform for DPCM

commit f34d57aa86a2d ("ASoC: soc-core: support dai_link with
platforms_num != 1") supports multi Platform, and
commit 60c54e8f584fc ("ASoC: simple-card-utils: consider CPU-Platform
possibility") removed no Platform from simple-card.

Multi Platform is now checking both Platform name/of_node are NULL case.
But in normal case, DPCM be doesn't have Platform.

asoc_simple_canonicalize_platform() try to use CPU of_node
to Platform (This is needed for DMAEngine platform case),
but it still might be NULL at DPCM be.

This patch try to use no Platform after that if Platform of_node
is still NULL. It can't probe without this patch.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87muhmgw2o.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>