sparc: fix sparse warnings in irq_32.c

Fix following sparse warnings:
symbol 'static_irqaction' was not declared. Should it be static?
symbol 'static_irq_count' was not declared. Should it be static?
symbol 'irq_action_lock' was not declared. Should it be static?
symbol 'unexpected_irq' was not declared. Should it be static?
symbol 'handler_irq' was not declared. Should it be static?
returning void-valued expression
returning void-valued expression
returning void-valued expression
symbol 'init_IRQ' was not declared. Should it be static?

Warnings were fixed by addding proper declarations
and fixing return path of a few functions.

There remains several warnings all related to the floppy driver.

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