mfd: staging: Constify struct mfd_cell where possible

As of commit 03e361b25ee8dfb1fd9b890072c23c4aae01c6c7 ("mfd: Stop setting
refcounting pointers in original mfd_cell arrays"), the "cell" parameter of
mfd_add_devices() is "const" again. Hence make all cell data passed to
mfd_add_devices() const where possible.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: devel@driverdev.osuosl.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/staging/nvec/nvec.c

@@ -83,7 +83,7 @@ enum nvec_sleep_subcmds {
 
 static struct nvec_chip *nvec_power_handle;
 
-static struct mfd_cell nvec_devices[] = {
+static const struct mfd_cell nvec_devices[] = {
 	{
 		.name = "nvec-kbd",
 		.id = 1,