staging: comedi: usbdux: fix sparse endianness warnings

Sparse has many warnings like:

drivers/staging/comedi/drivers/usbdux.c:366:32: warning: cast to
restricted __le16

on lines on which devpriv->in_buf or devpriv->insn_buf are passed to
le16_to_cpu().  This suggests that both of these variables should actually
be of type __le16.
Signed-off-by: Chase Southwood <chase.southwood@gmail.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/usbdux.c

@@ -196,9 +196,9 @@ struct usbdux_private {
 	/* size of the PWM buffer which holds the bit pattern */
 	int pwm_buf_sz;
 	/* input buffer for the ISO-transfer */
-	uint16_t *in_buf;
+	__le16 *in_buf;
 	/* input buffer for single insn */
-	uint16_t *insn_buf;
+	__le16 *insn_buf;
 
 	unsigned int high_speed:1;
 	unsigned int ai_cmd_running:1;