storage: Set all sdcards to visible,

[rohanpurohit]

If they are visibile to apps the media scanner will scan them.

Change-Id: Icceceafc8469b6b9d1c0e72f8425d7e38ae4a10b (cherry picked from commit 48dc2e83accb27b99c8a713b95988c25111c392b)