wifi: wcn36xx: Add debugfs entry to read firmware feature strings

Add in the ability to easily find the firmware feature bits reported in the
get feature exchange without having to compile-in debug prints.

root@linaro-alip:~# cat /sys/kernel/debug/ieee80211/phy0/wcn36xx/firmware_feat_caps
MCC
P2P
DOT11AC
SLM_SESSIONIZATION
DOT11AC_OPMODE
SAP32STA
TDLS
P2P_GO_NOA_DECOUPLE_INIT_SCAN
WLANACTIVE_OFFLOAD
BEACON_OFFLOAD
SCAN_OFFLOAD
BCN_MISS_OFFLOAD
STA_POWERSAVE
STA_ADVANCED_PWRSAVE
BCN_FILTER
RTT
RATECTRL
WOW
WLAN_ROAM_SCAN_OFFLOAD
SPECULATIVE_PS_POLL
IBSS_HEARTBEAT_OFFLOAD
WLAN_SCAN_OFFLOAD
WLAN_PERIODIC_TX_PTRN
ADVANCE_TDLS
BATCH_SCAN
FW_IN_TX_PATH
EXTENDED_NSOFFLOAD_SLOT
CH_SWITCH_V1
HT40_OBSS_SCAN
UPDATE_CHANNEL_LIST
WLAN_MCADDR_FLT
WLAN_CH144
TDLS_SCAN_COEXISTENCE
LINK_LAYER_STATS_MEAS
MU_MIMO
EXTENDED_SCAN
DYNAMIC_WMM_PS
MAC_SPOOFED_SCAN
FW_STATS
WPS_PRBRSP_TMPL
BCN_IE_FLT_DELTA

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220727161655.2286867-5-bryan.odonoghue@linaro.org

wcn36xx: mac80211 driver for Qualcomm WCN3660/WCN3680 hardware

This is a mac80211 driver for Qualcomm WCN3660/WCN3680 devices. So
far WCN3660/WCN3680 is available only on MSM platform.

Firmware can be found here:
https://www.codeaurora.org/cgit/external/hisense/platform/vendor/qcom-opensource/wlan/prima/tree/firmware_bin?h=8130_CS

Wiki page is available here:
http://wireless.kernel.org/en/users/Drivers/wcn36xx

A lot people made a contribution to this driver. Here is the list in
alphabetical order:

Eugene Krasnikov <k.eugene.e@gmail.com>
Kalle Valo <kvalo@qca.qualcomm.com>
Olof Johansson <dev@skyshaper.net>
Pontus Fuchs <pontus.fuchs@gmail.com>
Yanbo Li <yanbol@qti.qualcomm.com>

Signed-off-by: Eugene Krasnikov <k.eugene.e@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>