Use new ECP_LIGHT symbol in ecp_curves.c

Signed-off-by: Xiaokang Qian <xiaokang.qian@arm.com>
diff --git a/library/ecp_curves.c b/library/ecp_curves.c
index 408ace6..35ebc76 100644
--- a/library/ecp_curves.c
+++ b/library/ecp_curves.c
@@ -21,7 +21,7 @@
 
 #if !defined(MBEDTLS_ECP_WITH_MPI_UINT)
 
-#if defined(MBEDTLS_ECP_C)
+#if defined(MBEDTLS_ECP_LIGHT)
 
 #include "mbedtls/ecp.h"
 #include "mbedtls/platform_util.h"
@@ -5466,5 +5466,5 @@
 
 #endif /* !MBEDTLS_ECP_ALT */
 
-#endif /* MBEDTLS_ECP_C */
+#endif /* MBEDTLS_ECP_LIGHT */
 #endif /* MBEDTLS_ECP_WITH_MPI_UINT */