amdfwtool: Set flag comboable as bool type

Fix the CL:
https://review.coreboot.org/c/coreboot/+/58942
The type comboable was int but set as true.

Change-Id: Id2c43378735c089a27a5aa683b55a0f7ec3677de
Signed-off-by: Zheng Bao <fishbaozi@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59093
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

util/amdfwtool/amdfwtool.c

@@ -1274,7 +1274,7 @@ int main(int argc, char **argv)
 	char *rom = NULL;
 	embedded_firmware *amd_romsig;
 	psp_directory_table *pspdir;
-	int comboable = 0;
+	bool comboable = false;
 	int fuse_defined = 0;
 	int targetfd;
 	char *output = NULL, *config = NULL;