Revert "xfrm: Add possibility to set the default to block if we have no policy"

This reverts commit 5b7f84b1 which is
commit 2d151d39 upstream.

It breaks the Android kernel ABI and if this really needs to be added to
Android, it must come back in a format in the future that does not break
the abi.

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ic222a9dfeaa3775f1173b4cd13de7e9ae959ccd9