wifi: ath11k: factory test mode support

Add support to process factory test mode commands (FTM) for calibration.
By default firmware start with NORMAL mode and to process the FTM commands
firmware needs to be restarted in FTM mode using module parameter ftm_mode.
The pre-request is all the radios should be down before starting the test.

When start command ATH11K_TM_CMD_TESTMODE_START is received, ar->state
is set to Test Mode. If the FTM command or event length is greater
than 256 bytes, it will be broken down into multiple segments and
encoded with TLV header if it is segmented commands, else it is sent
to firmware as it is.

On receiving UTF event from firmware, if it is segmented event, the driver
will wait until it receives all the segments and notify the complete
data to user application. In case the segmented sequence are missed or
lost from the firmware, driver will skip the already received partial data.

In case of unsegmented UTF event from firmware, driver notifies the
data to the user application as it comes. Applications handles
the data further.

Command to boot in ftm mode:

insmod ath11k ftm_mode=1

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1

Signed-off-by: Govindaraj Saminathan <quic_gsaminat@quicinc.com>
Co-developed-by: Sowmiya Sree Elavalagan <quic_ssreeela@quicinc.com>
Signed-off-by: Sowmiya Sree Elavalagan <quic_ssreeela@quicinc.com>
Signed-off-by: Raj Kumar Bhagat <quic_rajkbhag@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230517135934.16408-4-quic_rajkbhag@quicinc.com