isa_no_iack_sc_device_interrupt() always gets get_irq_regs() as
argument; kill that argument.

All but two callers of handle_irq() pass get_irq_regs() as argument;
convert the remaining two, kill set_irq_regs() inside handle_irq().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>