staging: most: change dma_buf variable to __le16

dma_buf is being cast to __le16 *, but it was defined as u16 *.
sparse reported this error as:
drivers/staging/most/hdm-usb/hdm_usb.c:158:16: warning: cast to restricted
__le16

This patch changes dma_buf from u16 to __le16.
Signed-off-by: NRamiro Oliveira <Ramiro.Oliveira@synopsys.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/hdm-usb/hdm_usb.c

@@ -145,7 +145,7 @@ static void wq_netinfo(struct work_struct *wq_obj);
 static inline int drci_rd_reg(struct usb_device *dev, u16 reg, u16 *buf)
 {
 	int retval;
-	u16 *dma_buf = kzalloc(sizeof(u16), GFP_KERNEL);
+	__le16 *dma_buf = kzalloc(sizeof(__le16), GFP_KERNEL);
 	u8 req_type = USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE;
 
 	if (!dma_buf)