LinuxKPI: pm.h: add dummy pm_wakeup_event()

Add a dummy implementation of pm_wakeup_event() which is used to notify
the power management system about a wakeup (which we currently do not
implement yet).

Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Differential Revision: https://reviews.freebsd.org/D38239

sys/compat/linuxkpi/common/include/linux/pm.h

@@ -33,12 +33,15 @@
 #ifndef	_LINUXKPI_LINUX_PM_H
 #define	_LINUXKPI_LINUX_PM_H
 
+#include <linux/kernel.h>	/* pr_debug */
 #include <asm/atomic.h>
 
 /* Needed but breaks linux_usb.c */
 /* #include <linux/completion.h> */
 /* #include <linux/wait.h> */
 
+struct device;
+
 typedef struct pm_message {
 	int event;
 } pm_message_t;
@@ -85,4 +88,11 @@ const struct dev_pm_ops _name = {				\
 }
 #endif
 
+static inline void
+pm_wakeup_event(struct device *dev __unused, unsigned int x __unused)
+{
+
+	pr_debug("%s: TODO\n", __func__);
+}
+
 #endif	/* _LINUXKPI_LINUX_PM_H */