Remove unused function

mbedtls_oid_get_md_alg() is used in X.509, but
mbedtls_oid_get_oid_by_md() is only used in crypto.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/x509_oid.c b/library/x509_oid.c
index e8bd0d1..06a9e92 100644
--- a/library/x509_oid.c
+++ b/library/x509_oid.c
@@ -578,10 +578,5 @@
 
 FN_OID_TYPED_FROM_ASN1(oid_md_alg_t, md_alg, oid_md_alg)
 FN_OID_GET_ATTR1(mbedtls_x509_oid_get_md_alg, oid_md_alg_t, md_alg, mbedtls_md_type_t, md_alg)
-FN_OID_GET_OID_BY_ATTR1(mbedtls_x509_oid_get_oid_by_md,
-                        oid_md_alg_t,
-                        oid_md_alg,
-                        mbedtls_md_type_t,
-                        md_alg)
 
 #endif /* MBEDTLS_OID_C */