perf: Remove pointless union that wraps the hw breakpoint fields

It stands to anonymize a structure, but structures can already
anonymize by themselves.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "K. Prasad" <prasad@linux.vnet.ibm.com>

include/linux/perf_event.h

@@ -215,7 +215,6 @@ struct perf_event_attr {
 		__u32		wakeup_watermark; /* bytes before wakeup   */
 	};
 
-	union {
 	struct { /* Hardware breakpoint info */
 		__u64		bp_addr;
 		__u32		bp_type;
@@ -223,7 +222,6 @@ struct perf_event_attr {
 		__u64		__bp_reserved_1;
 		__u64		__bp_reserved_2;
 	};
-	};
 
 	__u32			__reserved_2;