tcg-ppc: Rename the tcg/ppc64 backend

The other tcg backends that support 32- and 64-bit modes
use the 32-bit name for the port.  Follow suit.

Tested-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Richard Henderson <rth@twiddle.net>

configure

@@ -4747,8 +4747,8 @@ elif test "$ARCH" = "s390x" ; then
   QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/s390 $QEMU_INCLUDES"
 elif test "$ARCH" = "x86_64" -o "$ARCH" = "x32" ; then
   QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/i386 $QEMU_INCLUDES"
-elif test "$ARCH" = "ppc" ; then
-  QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/ppc64 $QEMU_INCLUDES"
+elif test "$ARCH" = "ppc64" ; then
+  QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/ppc $QEMU_INCLUDES"
 else
   QEMU_INCLUDES="-I\$(SRC_PATH)/tcg/\$(ARCH) $QEMU_INCLUDES"
 fi