Solely use raw X.509 name data references including SEQUENCE header

So far, the CRT frame structure `mbedtls_x509_crt_frame` used
as `issuer_raw` and `subject_raw` the _content_ of the ASN.1
name structure for issuer resp. subject. This was in contrast
to the fields `issuer_raw` and `subject_raw` from the legacy
`mbedtls_x509_crt` structure, and caused some information
duplication by having both variants `xxx_no_hdr` and `xxx_with_hdr`
in `mbedtls_x509_crt` and `mbedtls_x509_crt_frame`.

This commit removes this mismatch by solely using the legacy
form of `issuer_raw` and `subject_raw`, i.e. those _including_
the ASN.1 name header.
diff --git a/library/x509_csr.c b/library/x509_csr.c
index d1a2760..23af9ae 100644
--- a/library/x509_csr.c
+++ b/library/x509_csr.c
@@ -183,15 +183,17 @@
         mbedtls_x509_csr_free( csr );
         return( MBEDTLS_ERR_X509_INVALID_FORMAT + ret );
     }
+    p += len;
+    csr->subject_raw.len = p - csr->subject_raw.p;
 
-    if( ( ret = mbedtls_x509_get_name( &p, p + len, &csr->subject ) ) != 0 )
+    if( ( ret = mbedtls_x509_get_name( csr->subject_raw.p,
+                                       csr->subject_raw.len,
+                                       &csr->subject ) ) != 0 )
     {
         mbedtls_x509_csr_free( csr );
         return( ret );
     }
 
-    csr->subject_raw.len = p - csr->subject_raw.p;
-
     /*
      *  subjectPKInfo SubjectPublicKeyInfo
      */