ath10k: don't enable interrupts for the diagnostic window

The diagnostic window (CE7) uses polling and is not initiliased to retrieve
interrupts so disable interrupts altogether for CE7. Otherwise ath10k crashes
when using the diagnostic window while the firmware is running due to NULL
dereference and polling reads timeout.

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: add diag_read() to hif ops

diag_read() is used for reading from firmware memory via the diagnose window.
First user will be cal_data debugfs file.

To serialise diagnostic window access and make it safe to use while firmware is
running take ce_lock both in ath10k_pci_diag_write_mem() and
ath10k_pci_diag_read_mem(). Because of that all the CE calls had to be changed
to _nolock variants.

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
ath10k: add cal_data debugfs file

Provide calibration data used by the firmware to user space via a debugfs file.
This makes it easier to debug calibration related problems.

Example:

sudo cp /sys/kernel/debug/ieee80211/phy0/ath10k/cal_data 1.cal

Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>