staging: vt6656: Replace embedded function name with __func__ in rf.c

Change embedded function name in vnt_rf_set_txpower with %s format with
__func__ argument to make it consistent with other part of if-else and
kernel coding style standards as reported by checkpatch.
Signed-off-by: Daniel Cashman <dan.a.cashman@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6656/rf.c

@@ -771,7 +771,7 @@ int vnt_rf_set_txpower(struct vnt_private *priv, u8 power, u32 rate)
 			ret &= vnt_rf_write_embedded(priv, 0x015C0800);
 		} else {
 			dev_dbg(&priv->usb->dev,
-				"@@@@ vnt_rf_set_txpower> 11G mode\n");
+				"@@@@ %s> 11G mode\n", __func__);
 
 			power_setting = ((0x3f - power) << 20) | (0x7 << 8);