libadfhwc: use %zu for logging size_t

Change-Id: Ica75935a194509f9d85d8e577b81f9de03aaaea4
Signed-off-by: Greg Hackmann <ghackmann@google.com>
diff --git a/adf/libadfhwc/adfhwc.cpp b/adf/libadfhwc/adfhwc.cpp
index dee3cae..57e09eb 100644
--- a/adf/libadfhwc/adfhwc.cpp
+++ b/adf/libadfhwc/adfhwc.cpp
@@ -257,7 +257,7 @@
 
         ret = adf_set_event(dup_intf_fd, ADF_EVENT_HOTPLUG, 1);
         if (ret < 0 && ret != -EINVAL) {
-            ALOGE("failed to enable hotplug event on display %u: %s",
+            ALOGE("failed to enable hotplug event on display %zu: %s",
                     i, strerror(errno));
             goto err;
         }