ath10k: fix core init failpath

HIF was not stopped properly in
ath10k_core_start() upon failure. This could cause
memory leaks of CE completions entries and
possibly other issues as well.

Move the HIF start/stop out of
ath10k_htc_wait_target(). The ctl_resp completion
is already prepared in ath10k_htc_init.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>