ath10k: fix PCIE device wake up failed

Observed PCIE device wake up failed after ~120 iterations of
soft-reboot test. The error message is
"ath10k_pci 0000:01:00.0: failed to wake up device : -110"

The call trace as below:
ath10k_pci_probe -> ath10k_pci_force_wake -> ath10k_pci_wake_wait ->
ath10k_pci_is_awake

Once trigger the device to wake up, we will continuously check the RTC
state until it returns RTC_STATE_V_ON or timeout.

But for QCA99x0 chips, we use wrong value for RTC_STATE_V_ON.
Occasionally, we get 0x7 on the fist read, we thought as a failure
case, but actually is the right value, also verified with the spec.
So fix the issue by changing RTC_STATE_V_ON from 0x5 to 0x7, passed
~2000 iterations.

Tested HW: QCA9984

Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>