backends: Use ebl->class consistently in sparc backend.

backends: Use ebl->class consistently in sparc backend.

sparc_init would check the ELF class to register to correct core_note
handler. But sparc_register_info would check the ELF machine to determine
whether the register set was 32 or 64 bits. This caused some confusion
and assertion failures in readelf when printing core notes where the
sparc machine and class didn't seem to match up. Check the ELF class
in both sparc_unit and sparc_register_info to give consistent results.

Signed-off-by: Mark Wielaard <mjw@redhat.com>