sparc64: Reschedule KGDB capture to a software interrupt.

Otherwise it might interrupt switch_to() midstream and use
half-cooked register window state.

Reported-by: Chris Torek <chris.torek@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc/include/asm/pil.h b/arch/sparc/include/asm/pil.h
index 32a7efe..26693703 100644
--- a/arch/sparc/include/asm/pil.h
+++ b/arch/sparc/include/asm/pil.h
@@ -24,6 +24,7 @@
 #define PIL_DEVICE_IRQ		5
 #define PIL_SMP_CALL_FUNC_SNGL	6
 #define PIL_DEFERRED_PCR_WORK	7
+#define PIL_KGDB_CAPTURE	8
 #define PIL_NORMAL_MAX		14
 #define PIL_NMI			15