ath11k: read and write registers below unwindowed address

For QCA6390, host can read and write registers below unwindowed
address directly without programming the window register. For
registers below bar0 + 4k - 32, host can read and write regardless
of the power save state. Shadow registers are located below
bar0 + 4K - 32.

Before MHI power up, there is no need to wakeup MHI so ini_done is
added to indicate it.

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/1601544890-13450-2-git-send-email-kvalo@codeaurora.org