ath10k: allow dynamic SAR power limits via common API

ath10k assigns ath10k_mac_set_sar_specs to ath10k_ops, and
this function is called when user space application calls
NL80211_CMD_SET_SAR_SPECS. ath10k also registers SAR type,
and supported frequency ranges to wiphy so user space can
query SAR capabilities.

This SAR power limitation is compared to regulatory txpower
and selects the minimal one to set when station is connected.
Otherwise, it delays until the station is connected. If the
station is disconnected, it returns to regulatory txpower.

This feature is controlled by hw parameter: dynamic_sar_support.

Tested-on: QCA6174 hw3.2 PCI WLAN.RM.4.4.1-00110-QCARMSWP-1

Signed-off-by: Carl Huang <cjhuang@codeaurora.org>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Abhishek Kumar <kuabhs@chromium.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20201203103728.3034-4-cjhuang@codeaurora.org