The conditional statement is missing parentheses

Add a ')' to the judgment statement.

Change-Id: Iadfdfb7643bc5224cb3029a2abb42c3c14982eef
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

src/corelib/doc/snippets/code/src_corelib_kernel_qdeadlinetimer.cpp

@@ -53,7 +53,7 @@
     {
         QDeadlineTimer deadline(msecs);
         do {
-            if (readFromDevice(deadline.remainingTime())
+            if (readFromDevice(deadline.remainingTime()))
                 break;
             waitForReadyRead(deadline);
         } while (!deadline.hasExpired());