wc_PKCS7_AddDataToStream() was called the first time prior to BERtoDER conversion, subsequent times afterwards which meant the stream idx pointer was incorrect. This patch restarts the stream after conversion. Fixes ZD13476
wc_PKCS7_AddDataToStream() was called the first time prior to BERtoDER conversion, subsequent times afterwards which meant the stream idx pointer was incorrect. This patch restarts the stream after conversion. Fixes ZD13476