Replace MBEDTLS_ERR_OID_BUF_TOO_SMALL with PSA_ERROR_BUFFER_TOO_SMALL

Remove the definition of `MBEDTLS_ERR_OID_BUF_TOO_SMALL` in `x509_oid.h`,
and use the corresponding PSA error instead.

```
git grep -l MBEDTLS_ERR_OID_BUF_TOO_SMALL | xargs perl -i -pe 's/\bMBEDTLS_ERR_OID_BUF_TOO_SMALL\b/PSA_ERROR_BUFFER_TOO_SMALL/p'
edit library/x509_oid.h
```

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index bbdd9f9..6a04ff0 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -2737,7 +2737,7 @@
 x509_oid_numstr:"2b06010505070301":"1.3.6.1.5.5.7.3.1":18:17
 
 X509 OID numstring #3 (buffer too small)
-x509_oid_numstr:"2b06010505070301":"1.3.6.1.5.5.7.3.1":17:MBEDTLS_ERR_OID_BUF_TOO_SMALL
+x509_oid_numstr:"2b06010505070301":"1.3.6.1.5.5.7.3.1":17:PSA_ERROR_BUFFER_TOO_SMALL
 
 X509 OID numstring #4 (larger number)
 x509_oid_numstr:"2a864886f70d":"1.2.840.113549":15:14