common: Drop linux/stringify.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/config_fsl_chain_trust.h b/include/config_fsl_chain_trust.h
index 4f522db..3922241 100644
--- a/include/config_fsl_chain_trust.h
+++ b/include/config_fsl_chain_trust.h
@@ -6,6 +6,8 @@
 #ifndef __CONFIG_FSL_CHAIN_TRUST_H
 #define __CONFIG_FSL_CHAIN_TRUST_H
 
+#include <linux/stringify.h>
+
 #ifdef CONFIG_CHAIN_OF_TRUST
 
 #ifndef CONFIG_EXTRA_ENV