mfd: fix tmio related warnings

We can not have .driver_data as const since platform_set_drvdata() doesnt take
a const.
The hclk mmc_data field can be const though.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/tc6393xb.c b/drivers/mfd/tc6393xb.c
index 9d2abb5..1429a73 100644
--- a/drivers/mfd/tc6393xb.c
+++ b/drivers/mfd/tc6393xb.c
@@ -136,7 +136,7 @@
 	return 0;
 }
 
-const static struct tmio_mmc_data tc6393xb_mmc_data = {
+static struct tmio_mmc_data tc6393xb_mmc_data = {
 	.hclk = 24000000,
 };