ANDROID: Incremental fs: Make files writeable

- added chmod() to +0222 to make all backing files and dirs
  writable. vold/system_server have a umask that clears those
  flags, making incfs unusable

Signed-off-by: Yurii Zubrytskyi <zyy@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
Bug: 133435829
Change-Id: Id9258401570cc2cc7cd5735aace89d379a9b043d
(cherry picked from commit bc5e5bc1d007e99228ca0717daa12639627819ba)