sparc32: fix sparse warnings in leon_smp.c

Fix following warnings:
leon_smp.c:133:6: warning: symbol 'leon_smp_setbroadcast' was not declared. Should it be static?
leon_smp.c:151:14: warning: symbol 'leon_smp_getbroadcast' was not declared. Should it be static?
leon_smp.c:269:6: warning: symbol 'leon_irq_rotate' was not declared. Should it be static?
leon_smp.c:355:6: warning: symbol 'leonsmp_ipi_interrupt' was not declared. Should it be static?
leon_smp.c:457:6: warning: symbol 'leon_cross_call_irq' was not declared. Should it be static?

Add static.
Remove unused functions.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>