staging/android: rename sync.h to sync_debug.h

This header file only contains information for debugging and SW_SYNC, so
rename it to sync_debug.h instead of having a more generic name.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>