mfd: rtsx_usb: Make mfd_cell array const

mfd_add_devices() expects array of struct mfd_cell to be const.
Signed-off-by: NKrzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: NRoger Tseng <rogerable@realtek.com>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/mfd/rtsx_usb.c

@@ -29,7 +29,7 @@ static int polling_pipe = 1;
 module_param(polling_pipe, int, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(polling_pipe, "polling pipe (0: ctl, 1: bulk)");
 
-static struct mfd_cell rtsx_usb_cells[] = {
+static const struct mfd_cell rtsx_usb_cells[] = {
 	[RTSX_USB_SD_CARD] = {
 		.name = "rtsx_usb_sdmmc",
 		.pdata_size = 0,