pinctrl: cy8c95x0: 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.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/pinctrl/pinctrl-cy8c95x0.c

@@ -20,6 +20,7 @@
 #include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/seq_file.h>
 
 #include <linux/pinctrl/pinctrl.h>
 #include <linux/pinctrl/pinconf.h>