Update lib/cifra/chacha20.c

Co-authored-by: Kazuho Oku <kazuhooku@gmail.com>
diff --git a/lib/cifra/chacha20.c b/lib/cifra/chacha20.c
index e51a930..03b06db 100644
--- a/lib/cifra/chacha20.c
+++ b/lib/cifra/chacha20.c
@@ -179,7 +179,7 @@
     return ret;
 }
 
-static void minicrypto_chacha20_aead_xor_iv(ptls_aead_context_t *_ctx, const void *_bytes, size_t len)
+static void chacha20poly1305_xor_iv(ptls_aead_context_t *_ctx, const void *_bytes, size_t len)
 {
     struct chacha20poly1305_context_t *ctx = (struct chacha20poly1305_context_t *)_ctx;
     const uint8_t *bytes = _bytes;