[POWERPC] irqtrace support for 64-bit powerpc

This adds the low level irq tracing hooks to the powerpc architecture
needed to enable full lockdep functionality.

This is partly based on Johannes Berg's initial version.  I removed
the asm trampoline that isn't needed (thus improving performance) and
modified all sorts of bits and pieces, reworking most of the assembly,
etc...

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/setup_64.c

@@ -33,6 +33,7 @@
 #include <linux/serial_8250.h>
 #include <linux/bootmem.h>
 #include <linux/pci.h>
+#include <linux/lockdep.h>
 #include <linux/lmb.h>
 #include <asm/io.h>
 #include <asm/kdump.h>
@@ -178,6 +179,9 @@ void __init early_setup(unsigned long dt_ptr)
 	/* Enable early debugging if any specified (see udbg.h) */
 	udbg_early_init();
 
+	/* Initialize lockdep early or else spinlocks will blow */
+	lockdep_init();
+
  	DBG(" -> early_setup(), dt_ptr: 0x%lx\n", dt_ptr);
 
 	/*