rootdir: goldfish: mount debugfs on boot time

goldfish is ported to linux-3.4 and have capability to run atrace.
But can't run atrace yet because debugfs is not mounted on boot time.

Change-Id: I0ce23bde3b8d1b2a88d4238272123e3ab8cb6970
Signed-off-by: Young-Ho Cha <ganadist@gmail.com>