x86: Support booting with TPL

Some boards want to use TPL as the first phase of U-Boot. This allows
selection of A or B SPL phases, thus allowing the memory init to be
upgraded in the field.

Add a new Kconfig option for this.
Signed-off-by: NSimon Glass <sjg@chromium.org>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>

arch/x86/Kconfig

@@ -176,10 +176,17 @@ config X86_16BIT_INIT
 config SPL_X86_16BIT_INIT
 	bool
 	depends on X86_RESET_VECTOR
-	default y if X86_RESET_VECTOR && SPL
+	default y if X86_RESET_VECTOR && SPL && !TPL
 	help
 	  This is enabled when 16-bit init is in SPL
 
+config TPL_X86_16BIT_INIT
+	bool
+	depends on X86_RESET_VECTOR
+	default y if X86_RESET_VECTOR && TPL
+	help
+	  This is enabled when 16-bit init is in TPL
+
 config X86_32BIT_INIT
 	bool
 	depends on X86_RESET_VECTOR