perf: Fix typos in comments

Fix two typos in kernel/events/*.

No change in functionality intended.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index d6b5618..5befb33 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -238,7 +238,7 @@ __weak void arch_unregister_hw_breakpoint(struct perf_event *bp)
 }
 
 /*
- * Contraints to check before allowing this new breakpoint counter:
+ * Constraints to check before allowing this new breakpoint counter:
  *
  *  == Non-pinned counter == (Considered as pinned for now)
  *