Remove references to some Montgomery curves

After all it looks like those won't become standard.
diff --git a/library/ecp.c b/library/ecp.c
index a802747..8703be0 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -98,10 +98,7 @@
 #define ECP_SHORTWEIERSTRASS
 #endif
 
-#if defined(MBEDTLS_ECP_DP_M221_ENABLED) ||   \
-    defined(MBEDTLS_ECP_DP_M255_ENABLED) ||   \
-    defined(MBEDTLS_ECP_DP_M383_ENABLED) ||   \
-    defined(MBEDTLS_ECP_DP_M511_ENABLED)
+#if defined(MBEDTLS_ECP_DP_M255_ENABLED)
 #define ECP_MONTGOMERY
 #endif
 
diff --git a/library/version_features.c b/library/version_features.c
index 47d93fd..20586fd 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -226,18 +226,9 @@
 #if defined(MBEDTLS_ECP_DP_BP512R1_ENABLED)
     "MBEDTLS_ECP_DP_BP512R1_ENABLED",
 #endif /* MBEDTLS_ECP_DP_BP512R1_ENABLED */
-#if defined(MBEDTLS_ECP_DP_M221_ENABLED)
-    "MBEDTLS_ECP_DP_M221_ENABLED",
-#endif /* MBEDTLS_ECP_DP_M221_ENABLED */
 #if defined(MBEDTLS_ECP_DP_M255_ENABLED)
     "MBEDTLS_ECP_DP_M255_ENABLED",
 #endif /* MBEDTLS_ECP_DP_M255_ENABLED */
-#if defined(MBEDTLS_ECP_DP_M383_ENABLED)
-    "MBEDTLS_ECP_DP_M383_ENABLED",
-#endif /* MBEDTLS_ECP_DP_M383_ENABLED */
-#if defined(MBEDTLS_ECP_DP_M511_ENABLED)
-    "MBEDTLS_ECP_DP_M511_ENABLED",
-#endif /* MBEDTLS_ECP_DP_M511_ENABLED */
 #if defined(MBEDTLS_ECP_NIST_OPTIM)
     "MBEDTLS_ECP_NIST_OPTIM",
 #endif /* MBEDTLS_ECP_NIST_OPTIM */