NFC: st21nfcb: Fix copy/paste error in comment

include/linux/platform_data/st21nfcb.h is based on
include/linux/platform_data/st21nfca.h.

The endif comment is inacurrate for st21nfcb.
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

include/linux/platform_data/st21nfcb.h

@@ -26,4 +26,4 @@ struct st21nfcb_nfc_platform_data {
 	unsigned int irq_polarity;
 };
 
-#endif /* _ST21NFCA_HCI_H_ */
+#endif /* _ST21NFCB_NCI_H_ */