The reservation mode of interrupts in kernel assigns a dummy vector
when the interrupt is allocated and assigns a real vector when the
request_irq is called. The reservation mode helps to ease vector
pressure when devices with a large amount of queues/interrupts
are initialized, but only a minimal subset of those queues/interrupts
is actually used.

So on reservation mode, the msi_data may change after request_irq
is called, so ath11k reads msi_data again after request_irq is called,
and then the correct msi_data is programmed into QCA6390 hardware
components. Without this change, spurious interrupt occurs in case of
one MSI vector. When VT-d in BIOS is enabled and ath11k can get 32 MSI
vectors, ath11k always get the same msi_data before and after request_irq,
that's why this change is only required when one MSI vector is to be
supported.

Tested-on: QCA6390 hw2.0 PCI WLAN.HST.1.0.1-01740-QCAHSTSWPLZ_V2_TO_X86-1
Signed-off-by: Carl Huang <cjhuang@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211026041636.5008-1-bqiang@codeaurora.org