psa: aead: Add missing chachapoly context free

Signed-off-by: Ronald Cron <ronald.cron@arm.com>
diff --git a/library/psa_crypto_aead.c b/library/psa_crypto_aead.c
index 57352c4..005dd33 100644
--- a/library/psa_crypto_aead.c
+++ b/library/psa_crypto_aead.c
@@ -65,6 +65,11 @@
             mbedtls_gcm_free( &operation->ctx.gcm );
             break;
 #endif /* MBEDTLS_PSA_BUILTIN_ALG_GCM */
+#if defined(MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305)
+        case PSA_ALG_CHACHA20_POLY1305:
+            mbedtls_chachapoly_free( &operation->ctx.chachapoly );
+            break;
+#endif /* MBEDTLS_PSA_BUILTIN_ALG_CHACHA20_POLY1305 */
     }
 }