scsi: move block/scsi.h to include/scsi/constants.h

Complete the transition by renaming this header, which was
shared by block/iscsi.c and the SCSI emulation code.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hw/scsi/megasas.c b/hw/scsi/megasas.c
index 734fdae..0db68aa 100644
--- a/hw/scsi/megasas.c
+++ b/hw/scsi/megasas.c
@@ -27,7 +27,7 @@
 #include "hw/pci/msix.h"
 #include "qemu/iov.h"
 #include "hw/scsi/scsi.h"
-#include "block/scsi.h"
+#include "scsi/constants.h"
 #include "trace.h"
 #include "qapi/error.h"
 #include "mfi.h"