powerpc/85xx: Cleanup handling of PVR detection for e500/e500mc/e5500

At some point we broke the detection of e500v1 class cores.  Fix that
and simply the code to just utilize PVR_VER() to have a single case
statement.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 9c4651a..0c4cc25 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -938,6 +938,10 @@
 #define PVR_85xx	0x80200000
 #define PVR_85xx_REV1	(PVR_85xx | 0x0010)
 #define PVR_85xx_REV2	(PVR_85xx | 0x0020)
+#define PVR_VER_E500_V1	0x8020
+#define PVR_VER_E500_V2	0x8021
+#define PVR_VER_E500MC	0x8023
+#define PVR_VER_E5500	0x8024
 
 #define PVR_86xx	0x80040000