greybus: audio: Rename widget_type to jack_attrubute

This fields actually populates jack attribute. Thus, renamed to
reflect the real purpose.

Signed-off-by: Vaibhav Agarwal <vaibhav.agarwal@linaro.org>
Reviewed-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>