spapr_pci: Include spapr.h instead of playing games with #error

include/hw/pci-host/spapr.h needs hw/ppc/spapr.h.  It checks whether
its header guard is defined, and errors out if it isn't.

Playing games with some other header's guard symbol is not a good
idea.  Just include the frackin' header already.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

include/hw/pci-host/spapr.h

@@ -16,13 +16,11 @@
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */
-#if !defined(__HW_SPAPR_H__)
-#error Please include spapr.h before this file!
-#endif
 
 #if !defined(__HW_SPAPR_PCI_H__)
 #define __HW_SPAPR_PCI_H__
 
+#include "hw/ppc/spapr.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_host.h"
 #include "hw/ppc/xics.h"