Replace all inclusions of config.h

Also remove preprocessor logic for MBEDTLS_CONFIG_FILE, since
build_info.h alreadyy handles it.

This commit was generated using the following script:

# ========================
#!/bin/sh
git ls-files | grep -v '^include/mbedtls/build_info\.h$' | xargs sed -b -E -i '
/^#if !?defined\(MBEDTLS_CONFIG_FILE\)/i#include "mbedtls/build_info.h"
//,/^#endif/d
'
# ========================

Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
diff --git a/programs/psa/key_ladder_demo.c b/programs/psa/key_ladder_demo.c
index 5d64349..cad875e 100644
--- a/programs/psa/key_ladder_demo.c
+++ b/programs/psa/key_ladder_demo.c
@@ -50,11 +50,7 @@
 /* First include Mbed TLS headers to get the Mbed TLS configuration and
  * platform definitions that we'll use in this program. Also include
  * standard C headers for functions we'll use here. */
-#if !defined(MBEDTLS_CONFIG_FILE)
-#include "mbedtls/config.h"
-#else
-#include MBEDTLS_CONFIG_FILE
-#endif
+#include "mbedtls/build_info.h"
 
 #include <stdlib.h>
 #include <stdio.h>