NFC: st21nfca: remove unnecessary variable and labels

assign vlue (EIO/EPROTO) to variable r, and goto exit label,
but just return r follow exit label, so we delete exit label,
and just replace with return sentence.

Signed-off-by: wengjianfeng <wengjianfeng@yulong.com>
Signed-off-by: David S. Miller <davem@davemloft.net>