powerpc/pseries: Add extended_cede_processor() helper function.

This patch provides an extended_cede_processor() helper function
which takes the cede latency hint as an argument. This hint is to be passed
on to the hypervisor to cede to the corresponding state on platforms
which support it.

Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/lppaca.h b/arch/powerpc/include/asm/lppaca.h
index f78f65c..14b592d 100644
--- a/arch/powerpc/include/asm/lppaca.h
+++ b/arch/powerpc/include/asm/lppaca.h
@@ -100,7 +100,14 @@
 	// Used to pass parms from the OS to PLIC for SetAsrAndRfid
 	u64	saved_gpr3;		// Saved GPR3                   x20-x27
 	u64	saved_gpr4;		// Saved GPR4                   x28-x2F
-	u64	saved_gpr5;		// Saved GPR5                   x30-x37
+	union {
+		u64	saved_gpr5;	/* Saved GPR5               x30-x37 */
+		struct {
+			u8	cede_latency_hint;  /*			x30 */
+			u8	reserved[7];        /*		    x31-x36 */
+		} fields;
+	} gpr5_dword;
+
 
 	u8	dtl_enable_mask;	// Dispatch Trace Log mask	x38-x38
 	u8	donate_dedicated_cpu;	// Donate dedicated CPU cycles  x39-x39