powerpc: Create arch/powerpc/platforms/iseries

I also move arch/ppc64/kernel/HvCall.c to
arch/powerpc/platforms/iseries/hvcall.c.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
diff --git a/arch/ppc64/Makefile b/arch/ppc64/Makefile
index 40675b3..d4eb55f 100644
--- a/arch/ppc64/Makefile
+++ b/arch/ppc64/Makefile
@@ -84,6 +84,7 @@
 libs-y				+= arch/ppc64/lib/
 core-y				+= arch/ppc64/kernel/
 core-y				+= arch/ppc64/mm/
+core-y				+= arch/powerpc/platforms/
 core-$(CONFIG_XMON)		+= arch/ppc64/xmon/
 drivers-$(CONFIG_OPROFILE)	+= arch/powerpc/oprofile/