sparc32: fix sparse warnings in sun4d_smp.c

Fix following warnings:
sun4d_smp.c:113:13: warning: symbol 'smp4d_boot_cpus' was not declared. Should it be static?
sun4d_smp.c:121:5: warning: symbol 'smp4d_boot_one_cpu' was not declared. Should it be static?
sun4d_smp.c:162:13: warning: symbol 'smp4d_smp_done' was not declared. Should it be static?
sun4d_smp.c:353:6: warning: symbol 'smp4d_cross_call_irq' was not declared. Should it be static?
sun4d_smp.c:363:6: warning: symbol 'smp4d_percpu_timer_interrupt' was not declared. Should it be static?

Add proper declarations

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: David S. Miller <davem@davemloft.net>