ath10k: Add chip reset sequence for QCA99X0

QCA99X0 supports only cold reset. Also, made
ath10k_pci_irq_msi_fw_mask() and ath10k_pci_irq_msi_fw_unmask()
non-99X0 specific till we get proper register configuration
to mask/unmask irq/MSI.

Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>