Set EX_SSS_BOOT_DO_ERASE to 0

If set to 1, all objects, which are handled by Secure chip except for
predefined ones, are deleted when a client application starts.
This breaks the logic of existing example, and functions "getbinkey",
"erasekey", and "decryptaes" start to fail because a requested key is
already removed when ex_sss_entry() is called.