Removes target_config.h file from default and thread configs

target_config.h is no longer needed for target/platform configurations so
this change removes it from the default and platform configurations for mbed
builds.

configs/config-thread.h

diff --git a/configs/config-thread.h b/configs/config-thread.h
index 453b17f..3193a04 100644
--- a/configs/config-thread.h
+++ b/configs/config-thread.h
@@ -85,10 +85,6 @@
 /* Save ROM and a few bytes of RAM by specifying our own ciphersuite list */
 #define MBEDTLS_SSL_CIPHERSUITES MBEDTLS_TLS_ECJPAKE_WITH_AES_128_CCM_8
 
-#if defined(TARGET_LIKE_MBED)
-#include "mbedtls/target_config.h"
-#endif
-
 #include "mbedtls/check_config.h"
 
 #endif /* MBEDTLS_CONFIG_H */

include/mbedtls/config.h

diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 86d8aa4..8b6de1b 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -2547,11 +2547,7 @@
 /* X509 options */
 //#define MBEDTLS_X509_MAX_INTERMEDIATE_CA   8   /**< Maximum number of intermediate CAs in a verification chain. */
 
-/* \} name SECTION: Module configuration options */
-
-#if defined(TARGET_LIKE_MBED)
-#include "mbedtls/target_config.h"
-#endif
+/* \} name SECTION: Customisation configuration options */
 
 /*
  * Allow user to override any previous default.