staging/android: move SW_SYNC_USER to a debugfs file

This remove CONFIG_SW_SYNC_USER and instead compile the sw_sync file into
debugpfs under <debugfs>/sync/sw_sync.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>