NFC: pn533: Staticize local symbols

Local symbols used only in this file are made static.
Signed-off-by: NSachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

drivers/nfc/pn533.c

@@ -2905,12 +2905,12 @@ static int pn533_rf_field(struct nfc_dev *nfc_dev, u8 rf)
 	return rc;
 }
 
-int pn533_dev_up(struct nfc_dev *nfc_dev)
+static int pn533_dev_up(struct nfc_dev *nfc_dev)
 {
 	return pn533_rf_field(nfc_dev, 1);
 }
 
-int pn533_dev_down(struct nfc_dev *nfc_dev)
+static int pn533_dev_down(struct nfc_dev *nfc_dev)
 {
 	return pn533_rf_field(nfc_dev, 0);
 }