perf tools: Fix message because cpu list option is -C not -c

Fix message because cpu list option is -C not -c
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1495786658-18063-19-git-send-email-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/session.c

@@ -2035,7 +2035,7 @@ int perf_session__cpu_bitmap(struct perf_session *session,
 
 		if (!(evsel->attr.sample_type & PERF_SAMPLE_CPU)) {
 			pr_err("File does not contain CPU events. "
-			       "Remove -c option to proceed.\n");
+			       "Remove -C option to proceed.\n");
 			return -1;
 		}
 	}