Remove extra mbedtls_ecp_group_free() call since the grp is free
at the top of the function.
diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 282481d..4335f2d 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -836,7 +836,6 @@
 #endif /* MBEDTLS_ECP_DP_CURVE448_ENABLED */
 
         default:
-            mbedtls_ecp_group_free( grp );
             return( MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE );
     }
 }