In the scenario where nbuf_map fails during packet
send in htc_issue_packets, restore_tx_packet done
as part of cleanup, does nbuf unmap even though map
failed.
Fix is to set the fixup_netbuf flag only if nbuf map
is successful.
Change-Id: I642eff15792a7e374434e5a7a05ad546af376b3a
CRs-Fixed: 2625765