cpu: Fix typo on freq_class

s/cpu_even_req/cpu_even_freq/

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
diff --git a/src/cpu/cpu.cpp b/src/cpu/cpu.cpp
index cc37748..96e3888 100644
--- a/src/cpu/cpu.cpp
+++ b/src/cpu/cpu.cpp
@@ -385,7 +385,7 @@
 	if (line & 1) {
 		return "cpu_odd_freq";
 	}
-	return "cpu_even_req";
+	return "cpu_even_freq";
 }
 
 static int has_state_level(class abstract_cpu *acpu, int state, int line)