ppc64: Minor compilation fixes

This defines CONFIG_PPC_STD_MMU for ppc64, changes an instance of
sys32_ to compat_sys_ in the ppc64 syscall table, and removes a
reference to a non-existent arch/powerpc/xmon/Makefile.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 29cda07..dedf121 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -131,7 +131,7 @@
 				   arch/powerpc/sysdev/ \
 				   arch/powerpc/platforms/
 core-$(CONFIG_MATH_EMULATION)	+= arch/ppc/math-emu/
-core-$(CONFIG_XMON)		+= arch/powerpc/xmon/
+#core-$(CONFIG_XMON)		+= arch/powerpc/xmon/
 core-$(CONFIG_APUS)		+= arch/ppc/amiga/
 drivers-$(CONFIG_8xx)		+= arch/ppc/8xx_io/
 drivers-$(CONFIG_4xx)		+= arch/ppc/4xx_io/