fix mixer config leak on config failure
fix mixer config leak on config failure

CID 1135539

rvandegrift/e,tizenorg/platform.upstream.enlightenment,rvandegrift/e,tasn/enlightenment,rvandegrift/e,tasn/enlightenment,FlorentRevest/Enlightenment,tasn/enlightenment,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment,FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment