display: remove compiler warnings

Use correct typecasts and format specifiers and resolve
compiler warnings

Change-Id: I51b12ecb78a9a496cf1f76c3d32892a203f70c43
diff --git a/libqdutils/idle_invalidator.cpp b/libqdutils/idle_invalidator.cpp
index d30375e..86191e9 100644
--- a/libqdutils/idle_invalidator.cpp
+++ b/libqdutils/idle_invalidator.cpp
@@ -103,7 +103,7 @@
             char data[64];
             // Consume the node by reading it
             ssize_t len = pread(pFd.fd, data, 64, 0);
-            ALOGD_IF(II_DEBUG, "IdleInvalidator::%s Idle Timeout fired len %zu",
+            ALOGD_IF(II_DEBUG, "IdleInvalidator::%s Idle Timeout fired len %zd",
                 __FUNCTION__, len);
             mHandler((void*)mHwcContext);
         }