Clean up CSTYLEDs

69 CSTYLED BEGINs remain, appx. 30 of which can be removed if cstyle(1)
had a useful policy regarding
  CALL(ARG1,
  	ARG2,
  	ARG3);
above 2 lines. As it stands, it spits out *both*
  sysctl_os.c: 385: continuation line should be indented by 4 spaces
  sysctl_os.c: 385: indent by spaces instead of tabs
which is very cool

Another >10 could be fixed by removing "ulong" &al. handling.
I don't foresee anyone actually using it intentionally
(does it even exist in modern headers? why did it in the first place?).

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12993

include/os/linux/spl/sys/mutex.h

@@ -113,8 +113,8 @@ spl_mutex_lockdep_on_maybe(kmutex_t *mp)			\
 	VERIFY3P(mutex_owner(mp), ==, NULL);			\
 }
 
-/* BEGIN CSTYLED */
 #define	mutex_tryenter(mp)					\
+/* CSTYLED */								\
 ({								\
 	int _rc_;						\
 								\
@@ -125,7 +125,6 @@ spl_mutex_lockdep_on_maybe(kmutex_t *mp)			\
 								\
 	_rc_;							\
 })
-/* END CSTYLED */
 
 #define	NESTED_SINGLE 1