secur32: Remove redendant call to gnutls_certificate_get_peers.

Two identical calls are made with the same parameters, and there are no
documented side effects of this function, so I removed one of them.

dlls/secur32/schannel.c

diff --git a/dlls/secur32/schannel.c b/dlls/secur32/schannel.c
index cd204c1..3912fbd 100644
--- a/dlls/secur32/schannel.c
+++ b/dlls/secur32/schannel.c
@@ -958,8 +958,7 @@
         case SECPKG_ATTR_REMOTE_CERT_CONTEXT:
         {
             unsigned int list_size;
-            const gnutls_datum_t *datum = pgnutls_certificate_get_peers(
-                    ctx->session, &list_size);
+            const gnutls_datum_t *datum;
 
             datum = pgnutls_certificate_get_peers(ctx->session, &list_size);
             if (datum)