powerpc: Make single-stepping emulation (mostly) usable on 32-bit

The sc instruction emulation can't be done the same way on 32-bit
as 64-bit yet, but this should work OK.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/include/asm-powerpc/reg.h b/include/asm-powerpc/reg.h
index 68058d7..bfb45a4 100644
--- a/include/asm-powerpc/reg.h
+++ b/include/asm-powerpc/reg.h
@@ -51,9 +51,17 @@
 #define __MASK(X)	(1UL<<(X))
 #endif
 
+#ifdef CONFIG_PPC64
 #define MSR_SF		__MASK(MSR_SF_LG)	/* Enable 64 bit mode */
 #define MSR_ISF		__MASK(MSR_ISF_LG)	/* Interrupt 64b mode valid on 630 */
 #define MSR_HV 		__MASK(MSR_HV_LG)	/* Hypervisor state */
+#else
+/* so tests for these bits fail on 32-bit */
+#define MSR_SF		0
+#define MSR_ISF		0
+#define MSR_HV		0
+#endif
+
 #define MSR_VEC		__MASK(MSR_VEC_LG)	/* Enable AltiVec */
 #define MSR_POW		__MASK(MSR_POW_LG)	/* Enable Power Management */
 #define MSR_WE		__MASK(MSR_WE_LG)	/* Wait State Enable */