[POWERPC] make spinlocks work in a combined kernel

If we build a pSeries/iSeries combined kernel, we will need this.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>

arch/powerpc/lib/locks.c

@@ -23,6 +23,7 @@
 #include <asm/hvcall.h>
 #include <asm/iseries/hv_call.h>
 #include <asm/smp.h>
+#include <asm/firmware.h>
 
 void __spin_yield(raw_spinlock_t *lock)
 {
@@ -39,13 +40,12 @@ void __spin_yield(raw_spinlock_t *lock)
 	rmb();
 	if (lock->slock != lock_value)
 		return;		/* something has changed */
-#ifdef CONFIG_PPC_ISERIES
-	HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
-		((u64)holder_cpu << 32) | yield_count);
-#else
-	plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
-			   yield_count);
-#endif
+	if (firmware_has_feature(FW_FEATURE_ISERIES))
+		HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
+			((u64)holder_cpu << 32) | yield_count);
+	else
+		plpar_hcall_norets(H_CONFER,
+			get_hard_smp_processor_id(holder_cpu), yield_count);
 }
 
 /*
@@ -69,13 +69,12 @@ void __rw_yield(raw_rwlock_t *rw)
 	rmb();
 	if (rw->lock != lock_value)
 		return;		/* something has changed */
-#ifdef CONFIG_PPC_ISERIES
-	HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
-		((u64)holder_cpu << 32) | yield_count);
-#else
-	plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
-			   yield_count);
-#endif
+	if (firmware_has_feature(FW_FEATURE_ISERIES))
+		HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
+			((u64)holder_cpu << 32) | yield_count);
+	else
+		plpar_hcall_norets(H_CONFER,
+			get_hard_smp_processor_id(holder_cpu), yield_count);
 }
 #endif