x86: samus: Add a target to boot through TPL

Add a version of samus which supports booting from TPL to SPL and then
to U-Boot. This allows TPL to select from an A or B SPL to support
verified boot with field upgrade.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/board/google/chromebook_samus/Kconfig b/board/google/chromebook_samus/Kconfig
index afbfe53..90c23cb 100644
--- a/board/google/chromebook_samus/Kconfig
+++ b/board/google/chromebook_samus/Kconfig
@@ -1,4 +1,4 @@
-if TARGET_CHROMEBOOK_SAMUS
+if TARGET_CHROMEBOOK_SAMUS || TARGET_CHROMEBOOK_SAMUS_TPL
 
 config SYS_BOARD
 	default "chromebook_samus"
@@ -10,7 +10,8 @@
 	default "broadwell"
 
 config SYS_CONFIG_NAME
-	default "chromebook_samus"
+	default "chromebook_samus" if TARGET_CHROMEBOOK_SAMUS
+	default "chromebook_samus" if TARGET_CHROMEBOOK_SAMUS_TPL
 
 config SYS_TEXT_BASE
 	default 0xffe00000
@@ -39,3 +40,12 @@
 	default 0x40000
 
 endif
+
+if TARGET_CHROMEBOOK_SAMUS_TPL
+
+config BOARD_SPECIFIC_OPTIONS_TPL # dummy
+	def_bool y
+	select SPL
+	select TPL
+
+endif