ath11k: pci: disable ASPM L0sLs before downloading firmware

Sometimes QCA6390 doesn't switch to amss state as device enters
L1ss state, so disable L0sL1s during firmware downloading.
Driver recovers the ASPM to default value in start callback
or powerdown callback.

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/1608218530-15426-1-git-send-email-kvalo@codeaurora.org