powerpc: Merge i8259.c into arch/powerpc/sysdev

This changes the parameters for i8259_init so that it takes two
parameters: a physical address for generating an interrupt
acknowledge cycle, and an interrupt number offset.  i8259_init
now sets the irq_desc[] for its interrupts; all the callers
were doing this, and that code is gone now.  This also defines
a CONFIG_PPC_I8259 symbol to select i8259.o for inclusion, and
makes the platforms that need it select that symbol.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/ppc/platforms/lopec.c b/arch/ppc/platforms/lopec.c
index 800c56a..06d247c 100644
--- a/arch/ppc/platforms/lopec.c
+++ b/arch/ppc/platforms/lopec.c
@@ -267,15 +267,11 @@
 	openpic_hookup_cascade(NUM_8259_INTERRUPTS, "82c59 cascade",
 			&i8259_irq);
 
-	/* Map i8259 interrupts */
-	for(i = 0; i < NUM_8259_INTERRUPTS; i++)
-		irq_desc[i].handler = &i8259_pic;
-
 	/*
 	 * The EPIC allows for a read in the range of 0xFEF00000 ->
 	 * 0xFEFFFFFF to generate a PCI interrupt-acknowledge transaction.
 	 */
-	i8259_init(0xfef00000);
+	i8259_init(0xfef00000, 0);
 }
 
 static int __init