ASoC: Correct the mixer control name

Change the mixer to match userspace mixer control.
Fix the null pointer dereference caused in soc core.
This null pointer exception was found in monkey run.

Change-Id: I0b3ca551fd2c057edd54a9771a13354ce6f0b7d2
Signed-off-by: Anish Kumar <kanish@codeaurora.org>