[SPARC32]: clean include/asm-sparc/irq.h

Move stuff used only by arch/sparc/kernel/* into arch/sparc/kernel/irq.h
and into individual files in there (e.g. macros internal to sun4m_irq.c,
etc.)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>