nfc: st-nci: fix memory leaks in EVT_TRANSACTION

Error path does not free previously allocated memory. Add devm_kfree() to
the failure path.

Reported-by: Denis Efremov <denis.e.efremov@oracle.com>
Reviewed-by: Guenter Roeck <groeck@google.com>
Fixes: 5d1ceb7f

 ("NFC: st21nfcb: Add HCI transaction event support")
Signed-off-by: Martin Faltesek <mfaltesek@google.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>