staging: tidspbridge: pmgr: dspapi.c: Cleaning up uninitialized variable

There is a risk that the variables will be used without being initialized.
Has also improved error handling, after an email proposal from Dan Carpenter.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>