Revert "Move dalvik-cache to /cache(64MB)"

Incremental update fails out of cache space (Settings app: 12MB)

There is no space in cache for the biggest system file.

This reverts commit ab2a3dd71c62d4237b60112156367b94c377d798.

Change-Id: I832b66d270a0f20047d5a97423c659c28caf3fa3