ath10k: fix possible ps sleep crash

ath10k: fix possible ps sleep crash

If probing failed pci sleep timer could remain
running and trigger after ath10k structures were
freed causing invalid pointer dereference:

 BUG: unable to handle kernel paging request at ffffc90001c80004
 IP: [<ffffffff81354728>] iowrite32+0x38/0x40
 ...
 Call Trace:
  <IRQ>
  [<ffffffffa00da048>] ? __ath10k_pci_sleep+0x48/0x60 [ath10k_pci]
  [<ffffffffa00da44e>] ath10k_pci_ps_timer+0x5e/0x80 [ath10k_pci]
  [<ffffffff810b210e>] call_timer_fn+0x3e/0x120
  [<ffffffffa00da3f0>] ? ath10k_pci_wake+0x150/0x150 [ath10k_pci]
  [<ffffffff810b3d11>] run_timer_softirq+0x201/0x2e0
  [<ffffffff8105d73f>] __do_softirq+0xaf/0x290
  [<ffffffff8105da95>] irq_exit+0x95/0xa0
  [<ffffffff81950406>] smp_apic_timer_interrupt+0x46/0x60
  [<ffffffff8194e77e>] apic_timer_interrupt+0x6e/0x80

Fixes: 77258d409ce4 ("ath10k: enable pci soc powersaving")
Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>