s/retreiv/retriev/g

As everyone knows, the rule is: "i before e.. um.. always."

Signed-off-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/drivers/usb/serial/ftdi_sio.h b/drivers/usb/serial/ftdi_sio.h
index 773ea3e..da004dd 100644
--- a/drivers/usb/serial/ftdi_sio.h
+++ b/drivers/usb/serial/ftdi_sio.h
@@ -714,7 +714,7 @@
  */
 
 /* FTDI_SIO_GET_MODEM_STATUS */
-/* Retreive the current value of the modem status register */
+/* Retrieve the current value of the modem status register */
 
 #define FTDI_SIO_GET_MODEM_STATUS_REQUEST_TYPE 0xc0
 #define FTDI_SIO_GET_MODEM_STATUS_REQUEST FTDI_SIO_GET_MODEM_STATUS