nfc: Add KCOV annotations

Add remote KCOV annotations for NFC processing that is done
in background threads. This enables efficient coverage-guided
fuzzing of the NFC subsystem.

The intention is to add annotations to background threads that
process skb's that were allocated in syscall context
(thus have a KCOV handle associated with the current fuzz test).
This includes nci_recv_frame() that is called by the virtual nci
driver in the syscall context.

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Bongsu Jeon <bongsu.jeon@samsung.com>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>