mfd: stmicro: 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.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/stmpe.h b/drivers/mfd/stmpe.h
index ff2b09b..6639f1b 100644
--- a/drivers/mfd/stmpe.h
+++ b/drivers/mfd/stmpe.h
@@ -38,7 +38,7 @@
  *		enable and altfunc callbacks
  */
 struct stmpe_variant_block {
-	struct mfd_cell		*cell;
+	const struct mfd_cell	*cell;
 	int			irq;
 	enum stmpe_block	block;
 };