blockdev: Fix error message for invalid -drive CHS

When cyls, heads or secs are out of range, the error message prints
buf, which points to the value of option "if".  Bogus, may even be
null.  Drop that.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

blockdev.c

@@ -224,15 +224,15 @@ DriveInfo *drive_init(QemuOpts *opts, int default_to_scsi, int *fatal_error)
 
     if (cyls || heads || secs) {
         if (cyls < 1 || (type == IF_IDE && cyls > 16383)) {
-            fprintf(stderr, "qemu: '%s' invalid physical cyls number\n", buf);
+            fprintf(stderr, "qemu: invalid physical cyls number\n");
 	    return NULL;
 	}
         if (heads < 1 || (type == IF_IDE && heads > 16)) {
-            fprintf(stderr, "qemu: '%s' invalid physical heads number\n", buf);
+            fprintf(stderr, "qemu: invalid physical heads number\n");
 	    return NULL;
 	}
         if (secs < 1 || (type == IF_IDE && secs > 63)) {
-            fprintf(stderr, "qemu: '%s' invalid physical secs number\n", buf);
+            fprintf(stderr, "qemu: invalid physical secs number\n");
 	    return NULL;
 	}
     }