[bssl] Move ec_key module from rialto to libbssl

Bug: 301068421
Test: atest rialto_test
Change-Id: I04f3040f79f1af18b5c76546adcd6616aa052729
diff --git a/libs/bssl/src/lib.rs b/libs/bssl/src/lib.rs
index a4e00f0..85890ee 100644
--- a/libs/bssl/src/lib.rs
+++ b/libs/bssl/src/lib.rs
@@ -16,7 +16,11 @@
 
 #![cfg_attr(not(feature = "std"), no_std)]
 
+extern crate alloc;
+
 mod cbb;
+mod ec_key;
 
 pub use bssl_avf_error::{ApiName, Error, Result};
 pub use cbb::CbbFixed;
+pub use ec_key::{EcKey, ZVec};