Really sort out the headers.

sys/systm.h must always come after sys/param.h.

Remove sys/types.h which should never be included together with sys/param.h.

Add sys/malloc.h for correctness even if it seems to don't be needed.

Remove more unused headers found by unusedinc (from bde@) and tested with a
universe build.

Reported by:	bde

sys/dev/gpio/gpiobus.c

@@ -28,13 +28,11 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
+#include <sys/systm.h>
 #include <sys/bus.h>
-#include <sys/gpio.h>
 #include <sys/kernel.h>
 #include <sys/malloc.h>
 #include <sys/module.h>
-#include <sys/systm.h>
-#include <sys/types.h>
 
 #include <dev/gpio/gpiobusvar.h>
 

sys/dev/gpio/gpiobusvar.h

@@ -32,7 +32,6 @@
 
 #include "opt_platform.h"
 
-#include <sys/param.h>
 #include <sys/lock.h>
 #include <sys/mutex.h>
 

sys/dev/gpio/ofw_gpiobus.c

@@ -30,18 +30,16 @@
 __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
-#include <sys/bus.h>
-#include <sys/gpio.h>
-#include <sys/kernel.h>
-#include <sys/module.h>
 #include <sys/systm.h>
+#include <sys/bus.h>
+#include <sys/kernel.h>
+#include <sys/malloc.h>
+#include <sys/module.h>
 
 #include <dev/gpio/gpiobusvar.h>
 #include <dev/ofw/ofw_bus.h>
-#include <dev/ofw/openfirm.h>
 
 #include "gpio_if.h"
-#include "gpiobus_if.h"
 
 static int ofw_gpiobus_parse_gpios(struct gpiobus_softc *,
     struct gpiobus_ivar *, phandle_t);