tests: Remove redundant assignment

Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

tests/postcopy-test.c

@@ -41,7 +41,7 @@ static bool ufd_version_check(void)
     struct uffdio_api api_struct;
     uint64_t ioctl_mask;
 
-    int ufd = ufd = syscall(__NR_userfaultfd, O_CLOEXEC);
+    int ufd = syscall(__NR_userfaultfd, O_CLOEXEC);
 
     if (ufd == -1) {
         g_test_message("Skipping test: userfaultfd not available");