timekeeping: Fix kerneldoc system_device_crosststamp & al

Make kernel doc comments actually work and fix the syncronized typo.

[ tglx: Added the missing /** and fixed up formatting ]
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200609081726.5657-1-kurt@linutronix.de

include/linux/timekeeping.h

@@ -222,7 +222,7 @@ extern bool timekeeping_rtc_skipresume(void);
 
 extern void timekeeping_inject_sleeptime64(const struct timespec64 *delta);
 
-/*
+/**
  * struct system_time_snapshot - simultaneous raw/real time capture with
  *				 counter value
  * @cycles:	Clocksource counter value to produce the system times
@@ -239,9 +239,9 @@ struct system_time_snapshot {
 	u8		cs_was_changed_seq;
 };
 
-/*
+/**
  * struct system_device_crosststamp - system/device cross-timestamp
- *	(syncronized capture)
+ *				      (synchronized capture)
  * @device:		Device time
  * @sys_realtime:	Realtime simultaneous with device time
  * @sys_monoraw:	Monotonic raw simultaneous with device time
@@ -252,7 +252,7 @@ struct system_device_crosststamp {
 	ktime_t sys_monoraw;
 };
 
-/*
+/**
  * struct system_counterval_t - system counter value with the pointer to the
  *				corresponding clocksource
  * @cycles:	System counter value