powerpc: Rename 64-bit PVR constants to PVR_foo

We have an old FIXME in reg.h which points out that we should standardise
on PVR_foo for our PVR #defines. Currently we use PVR_ on 32-bit and PV_
on 64-bit.

So do that rename and remove the FIXME.

Seeing as we're touching all but one usage of __is_processor(), rename it
to something less ugly and more indicative of what it does, which is
simply to check the PVR version.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 0794a30..ce68278 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -1691,7 +1691,7 @@
 		 * else will impact performance, so we always allocate 8MB.
 		 * Anton
 		 */
-		if (__is_processor(PV_POWER4) || __is_processor(PV_POWER4p))
+		if (pvr_version_is(PVR_POWER4) || pvr_version_is(PVR_POWER4p))
 			minsize = 8UL << 20;
 		else
 			minsize = 4UL << 20;