greybus: audio: fix uninitialized variable errors found by cppcheck

Currently, if info is null, the dev_err message is dereferencing an
uninitialized module pointer.  Instead, it should use codec->dev pointer
in dev_err call and better align with other err msg in this function.

Also, ret variable might be used uninitialized in a specific case.
Avoid using it this way.

Found using static analysis with cppcheck:
Checking drivers/staging/greybus/audio_topology.c...
[drivers/staging/greybus/audio_topology.c:175]: (error) Uninitialized
variable: module
[drivers/staging/greybus/audio_topology.c:495]: (error) Uninitialized
variable: ret

Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>