amdfwtool: Add options to support mainboard specific SPL table

For the generic board which uses Cezanne, we use the generic SPL
table. For the Guybrush Chromebook, we need to use a customized SPL
file.

BUG=b:216096562

Change-Id: I385b0fe13cb78a053c07127ec3ea1c61dc42c7e4
Signed-off-by: Zheng Bao <fishbaozi@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61836
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

util/amdfwtool/amdfwtool.h

@@ -251,6 +251,7 @@ typedef struct _amd_cb_config {
 	bool load_mp2_fw;
 	bool multi_level;
 	bool s0i3;
+	bool have_mb_spl;
 } amd_cb_config;
 
 void register_fw_fuse(char *str);