util: Remove NONNULL(1) for virHostdevPrepareDomainDevices

Since the code checks 'mgr == NULL' anyway, no need for the prototype
to have the NONNULL arg check.  Also add an error message to indicate what
the failure is so that there isn't a failed for some reason error.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

src/util/virhostdev.c

@@ -1873,8 +1873,11 @@ virHostdevPrepareDomainDevices(virHostdevManagerPtr mgr,
     if (!def->nhostdevs)
         return 0;
 
-    if (mgr == NULL)
+    if (!mgr) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("no host device manager defined"));
         return -1;
+    }
 
     if (flags & VIR_HOSTDEV_SP_PCI) {
         if (virHostdevPreparePCIDevices(mgr, driver,

src/util/virhostdev.h

@@ -157,7 +157,7 @@ virHostdevPrepareDomainDevices(virHostdevManagerPtr mgr,
                                const char *driver,
                                virDomainDefPtr def,
                                unsigned int flags)
-    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
+    ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3);
 void
 virHostdevReAttachDomainDevices(virHostdevManagerPtr mgr,
                                 const char *driver,