ASoC: soc-core: snd_soc_rtdcom_lookup() cares component driver name

snd_soc_rtdcom_lookup() look up component by uisng driver name.
Then, it uses component->driver->name.
Some driver might doesn't have it, thus it should care NULL pointer.
This patch solve this issue.

Reported-by: Mukunda,Vijendar <vijendar.mukunda@amd.com>
Reported-by: Manuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Mukunda,Vijendar <vijendar.mukunda@amd.com>
Signed-off-by: Mark Brown <broonie@kernel.org>