Increase debug level of Xen detection code.

Now that Xen is enabled by default the detection code will frequently
not find a valid Xen hypervisor signature, so don't spam the debug
logs.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
diff --git a/src/xen.c b/src/xen.c
index 41aab98..a4669d0 100644
--- a/src/xen.c
+++ b/src/xen.c
@@ -62,7 +62,7 @@
         memcpy(signature + 8, &edx, 4);
         signature[12] = 0;
 
-        dprintf(1, "Found hypervisor signature \"%s\" at %x\n",
+        dprintf(9, "Found hypervisor signature \"%s\" at %x\n",
                 signature, base);
         if (strcmp(signature, "XenVMMXenVMM") == 0) {
             /* Set debug_io_port first, so the following messages work. */