Several packets are sent to firmware in htt_htc_attach_all(), back to
back. However, if one of the latter packets fails to send for some
reason, the previous packets are not flushed. This leads to a number of
leaks under error conditions.
If a packet fails to send in htt_htc_attach_all(), flush the endpoint
before returning failure to the upper layers.
Change-Id: If9b33a645f7bcc77442e18566525ae57b544f1a0
CRs-Fixed: 2219137
95ff87c60e