sync: refactor sync debug printing

Move driver callbacks to fill strings instead of using seq_files.  This
will allow those values to be used in a future tracepoint patch.

Change-Id: I9b706343e35b11124141fe520e520514a32003d2
Signed-off-by: Erik Gilling <konkers@android.com>
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>
2 files changed