staging: rtl8188eu: correct spelling mistake in a comment

Correct spelling mistake in a comment reported by checkpatch.
checksumed -> checksummed

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/os_dep/usb_ops_linux.c

@@ -273,7 +273,7 @@ static int usbctrl_vendorreq(struct adapter *adapt, u8 request, u16 value, u16 i
 			}
 		}
 
-		/*  firmware download is checksumed, don't retry */
+		/*  firmware download is checksummed, don't retry */
 		if ((value >= FW_8188E_START_ADDRESS && value <= FW_8188E_END_ADDRESS) || status == len)
 			break;
 	}