perf tools: Add the right header to obtain PERF_ALIGN()

The util/event.h header needs PERF_ALIGN(), but wasn't including
linux/kernel.h, where it is defined, instead it was getting it by
luck by including map.h, which it doesn't need at all.

Fix it by including the right header.

Link: http://lkml.kernel.org/n/tip-nf3t9blzm5ncoxsczi8oy9mx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/event.h

@@ -3,9 +3,9 @@
 
 #include <limits.h>
 #include <stdio.h>
+#include <linux/kernel.h>
 
 #include "../perf.h"
-#include "map.h"
 #include "build-id.h"
 #include "perf_regs.h"