ps3: add elfv2 support

ps3 are broken since we moved to clang/elfv2. Fix this by updating the
hypercall glue to the new ABI.

Signed-off-by: Chattrapat Sangmanee <aomsin27@hotmail.co.th>
Reviewed by: jhibbits
MFC after: 1 week
Pull Request: https://github.com/freebsd/freebsd-src/pull/1413