pinctrl: get_group_pins() const fixes

get_group_pins() "returns" a pointer to an array of const objects, through
a pointer parameter. Fix the prototype so what's pointed at by the returned
pointer is const, rather than the function parameter being const.

This also allows the removal of a cast in each of the two current pinmux
drivers.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
index b2eaf8d..ceb6327 100644
--- a/drivers/pinctrl/core.c
+++ b/drivers/pinctrl/core.c
@@ -329,7 +329,7 @@
 
 	seq_puts(s, "registered pin groups:\n");
 	while (ops->list_groups(pctldev, selector) >= 0) {
-		unsigned *pins;
+		const unsigned *pins;
 		unsigned num_pins;
 		const char *gname = ops->get_group_name(pctldev, selector);
 		int ret;