msm: qdsp: fix aac encoder configuration validation

Unsupported encoder configuration was getting forwarded to
DSP causing encode failure at latter stage.
Corrected encoder validation logic which would throw
error for unsupported configuration values and would use
default conf in such cases, preventing failure at latter
stage where error from dsp cannot be handled gracefully.
Also updated userspace to driver format mapping.

CRs-Fixed: 621150
Change-Id: Id049425ac12fa076ad2891f563da67a103630383
Signed-off-by: Dhananjay Kumar <dhakumar@codeaurora.org>