Replace hash_info macro with MD macro

Now the MD macro also accounts for PSA-only hashes.

Just a search-and-replace, plus manually removing the definition in
hash_info.h.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/library/x509write_csr.c b/library/x509write_csr.c
index deb6617..06f5c93 100644
--- a/library/x509write_csr.c
+++ b/library/x509write_csr.c
@@ -243,7 +243,7 @@
     const char *sig_oid;
     size_t sig_oid_len = 0;
     unsigned char *c, *c2;
-    unsigned char hash[MBEDTLS_HASH_MAX_SIZE];
+    unsigned char hash[MBEDTLS_MD_MAX_SIZE];
     size_t pub_len = 0, sig_and_oid_len = 0, sig_len;
     size_t len = 0;
     mbedtls_pk_type_t pk_alg;