sync: add oneshot sync driver

Add /dev/oneshot_sync. This driver is similar to /dev/sw_sync
except that sync events may be fired in order rather than
enforcing a timeline model.

Change-Id: I152d25a45a01a2ff159e8c64e621dce6c9905470
Signed-off-by: Jeremy Gebben <jgebben@codeaurora.org>