Add config.h option MBEDTLS_ECP_NO_INTERNAL_RNG

No effect so far, except on dependency checking, as the feature it's meant to
disable isn't implemented yet (so the descriptions in config.h and the
ChangeLog entry are anticipation for now).

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/scripts/config.pl b/scripts/config.pl
index ba563d6..72aabf6 100755
--- a/scripts/config.pl
+++ b/scripts/config.pl
@@ -73,6 +73,7 @@
 MBEDTLS_CTR_DRBG_USE_128_BIT_KEY
 MBEDTLS_DEPRECATED_REMOVED
 MBEDTLS_DEPRECATED_WARNING
+MBEDTLS_ECP_NO_INTERNAL_RNG
 MBEDTLS_HAVE_SSE2
 MBEDTLS_MEMORY_BACKTRACE
 MBEDTLS_MEMORY_BUFFER_ALLOC_C