target-ppc: Remove unnecessary variable

Compress lines and remove the variable.
Signed-off-by: NShraddha Barke <shraddha.6596@gmail.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

target-ppc/kvm.c

@@ -1782,8 +1782,7 @@ uint32_t kvmppc_get_tbfreq(void)
 
     ns++;
 
-    retval = atoi(ns);
-    return retval;
+    return atoi(ns);
 }
 
 bool kvmppc_get_host_serial(char **value)