arch: sparc: kernel: starfire.c: Remove unused function

Remove the function starfire_hard_smp_processor_id() that is not used anywhere.

This was partially found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: David S. Miller <davem@davemloft.net>