x86: Add a CPU init function for TPL

For TPL we only need to set up the features and identify the CPU to a
basic level. Add a function to handle that.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/include/asm/u-boot-x86.h b/arch/x86/include/asm/u-boot-x86.h
index 2466ad2..3e5d56d 100644
--- a/arch/x86/include/asm/u-boot-x86.h
+++ b/arch/x86/include/asm/u-boot-x86.h
@@ -34,6 +34,15 @@
  */
 int x86_cpu_reinit_f(void);
 
+/**
+ * x86_cpu_init_tpl() - Do the minimum possible CPU init
+ *
+ * This just sets up the CPU features and figured out the identity
+ *
+ * @return 0 (indicating success, to mimic cpu_init_f())
+ */
+int x86_cpu_init_tpl(void);
+
 int cpu_init_f(void);
 void setup_gdt(struct global_data *id, u64 *gdt_addr);
 /*