Remove compilation option MBEDTLS_PSA_HAS_ITS_IO

MBEDTLS_PSA_HAS_ITS_IO is not really useful since it doesn't actually
enable anything except the entropy seed file support, which only
requires the ITS interface and not a native implemetation. Remove it.
diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index f27b50e..a358a20 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -1166,16 +1166,6 @@
  */
 //#define MBEDTLS_ENTROPY_NV_SEED
 
-/**
- * \def MBEDTLS_PSA_HAS_ITS_IO
- *
- * Enable the non-volatile secure storage usage.
- *
- * This is crucial on systems that do not have a HW TRNG support.
- *
- */
-//#define MBEDTLS_PSA_HAS_ITS_IO
-
 /* MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER
  *
  * In PSA key storage, encode the owner of the key.
@@ -1262,16 +1252,6 @@
 //#define MBEDTLS_PSA_CRYPTO_SPM
 
 /**
- * \def MBEDTLS_PSA_HAS_ITS_IO
- *
- * Enable the non-volatile secure storage usage.
- *
- * This is crucial on systems that do not have a HW TRNG support.
- *
- */
-//#define MBEDTLS_PSA_HAS_ITS_IO
-
-/**
  * \def MBEDTLS_RSA_NO_CRT
  *
  * Do not use the Chinese Remainder Theorem
diff --git a/include/psa/crypto_extra.h b/include/psa/crypto_extra.h
index 5dd4789..545dd4b 100644
--- a/include/psa/crypto_extra.h
+++ b/include/psa/crypto_extra.h
@@ -115,7 +115,7 @@
  *
  * \note This function is only available on the following platforms:
  * * If the compile-time options MBEDTLS_ENTROPY_NV_SEED and
- *   MBEDTLS_PSA_HAS_ITS_IO are both enabled. Note that you
+ *   MBEDTLS_PSA_CRYPTO_STORAGE_C are both enabled. Note that you
  *   must provide compatible implementations of mbedtls_nv_seed_read
  *   and mbedtls_nv_seed_write.
  * * In a client-server integration of PSA Cryptography, on the client side,