pinctrl: k210: Add missing header(s)

Do not imply that some of the generic headers may be always included.
Instead, include explicitly what we are direct user of.

While at it, sort headers alphabetically.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

drivers/pinctrl/pinctrl-k210.c

@@ -3,18 +3,20 @@
  * Copyright (C) 2020 Sean Anderson <seanga2@gmail.com>
  * Copyright (c) 2020 Western Digital Corporation or its affiliates.
  */
-#include <linux/io.h>
-#include <linux/of_device.h>
+#include <linux/bitfield.h>
 #include <linux/clk.h>
+#include <linux/io.h>
 #include <linux/mfd/syscon.h>
+#include <linux/of_device.h>
 #include <linux/platform_device.h>
-#include <linux/bitfield.h>
 #include <linux/regmap.h>
+#include <linux/seq_file.h>
 #include <linux/slab.h>
+
+#include <linux/pinctrl/pinconf-generic.h>
+#include <linux/pinctrl/pinconf.h>
 #include <linux/pinctrl/pinctrl.h>
 #include <linux/pinctrl/pinmux.h>
-#include <linux/pinctrl/pinconf.h>
-#include <linux/pinctrl/pinconf-generic.h>
 
 #include <dt-bindings/pinctrl/k210-fpioa.h>