pinctrl: some typo fixes

Minor copyedits.

Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 3bcc641..0916222 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -342,7 +342,7 @@
  * Only call this once during initialization of your machine, the function is
  * tagged as __init and won't be callable after init has completed. The map
  * passed into this function will be owned by the pinmux core and cannot be
- * free:d.
+ * freed.
  */
 int __init pinmux_register_mappings(struct pinmux_map const *maps,
 				    unsigned num_maps)