ath10k: fix core start sequence

It was possible to call hif_stop() 2 times through
ath10k_htc_connect_init() timeout failpath which
could lead to double free_irq() kernel splat for
multiple MSI interrupt case.

Re-order init sequence to avoid this problem. The
HTC stop shouldn't stop HIF implicitly since it
doesn't implicitly start it. Since the re-ordering
required some functions to be split/removed/renamed
rename a few functions to make more sense while at
it.

Reported-By: Ben Greear <greearb@candelatech.com>
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: prevent hif_stop being called twice

Recently there was a bug discovered that involved
hif_stop() being called twice that ended up with a
double free_irq() call but it only manifested with
multiple MSI interrupts mapping.

Catch this kind of a problem early in driver
regardless of interrupt mapping.

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