target-xtensa: make default CPU depend on target endianness

This makes usable default for -cpu option both for qemu-system-xtensa
and qemu-system-xtensaeb fixing the following error:

    $ qemu-system-xtensaeb -M sim
    Unable to find CPU definition

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/hw/xtensa_sim.c b/hw/xtensa_sim.c
index 1ce07fb..ed38bd4 100644
--- a/hw/xtensa_sim.c
+++ b/hw/xtensa_sim.c
@@ -102,7 +102,7 @@
                      const char *initrd_filename, const char *cpu_model)
 {
     if (!cpu_model) {
-        cpu_model = "dc232b";
+        cpu_model = XTENSA_DEFAULT_CPU_MODEL;
     }
     sim_init(ram_size, boot_device, kernel_filename, kernel_cmdline,
             initrd_filename, cpu_model);
@@ -110,7 +110,7 @@
 
 static QEMUMachine xtensa_sim_machine = {
     .name = "sim",
-    .desc = "sim machine (dc232b)",
+    .desc = "sim machine (" XTENSA_DEFAULT_CPU_MODEL ")",
     .init = xtensa_sim_init,
     .max_cpus = 4,
 };