perf tools: Fix typo: "ehough" -> "enough"

Trivial typo fix in pr_debug message
Signed-off-by: Colin King <colin.king@canonical.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20160821141256.7530-1-colin.king@canonical.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/backward-ring-buffer.c

@@ -97,7 +97,7 @@ int test__backward_ring_buffer(int subtest __maybe_unused)
 
 	evlist = perf_evlist__new();
 	if (!evlist) {
-		pr_debug("No ehough memory to create evlist\n");
+		pr_debug("No enough memory to create evlist\n");
 		return TEST_FAIL;
 	}