selftests:kvm: fix get_trans_hugepagesz() ignoring fscanf() return warn

Fix get_trans_hugepagesz() to check fscanf() return value to get rid
of the following warning:

lib/test_util.c: In function ‘get_trans_hugepagesz’:
lib/test_util.c:138:2: warning: ignoring return value of ‘fscanf’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
  138 |  fscanf(f, "%ld", &size);
      |  ^~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/kvm/lib/test_util.c

@@ -129,13 +129,16 @@ size_t get_trans_hugepagesz(void)
 {
 	size_t size;
 	FILE *f;
+	int ret;
 
 	TEST_ASSERT(thp_configured(), "THP is not configured in host kernel");
 
 	f = fopen("/sys/kernel/mm/transparent_hugepage/hpage_pmd_size", "r");
 	TEST_ASSERT(f != NULL, "Error in opening transparent_hugepage/hpage_pmd_size");
 
-	fscanf(f, "%ld", &size);
+	ret = fscanf(f, "%ld", &size);
+	ret = fscanf(f, "%ld", &size);
+	TEST_ASSERT(ret < 1, "Error reading transparent_hugepage/hpage_pmd_size");
 	fclose(f);
 
 	return size;