Add missing TlclLibClose function for mock TPM interface

BUG=none
BRANCH=none
TEST=manual: MOCK_TPM=1 emerge vboot_reference

Change-Id: I81ae9bb646b1a1186629e1a3ba8317efe8397faf
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/41131
Reviewed-by: Bill Richardson <wfrichar@chromium.org>

firmware/lib/tpm_lite/mocked_tlcl.c

@@ -12,6 +12,10 @@ uint32_t TlclLibInit(void) {
   return VbExTpmInit();
 }
 
+uint32_t TlclLibClose(void) {
+  return TPM_SUCCESS;
+}
+
 uint32_t TlclStartup(void) {
   return TPM_SUCCESS;
 }