iw: add set sar_specs command

iw: add set sar_specs command

Add set sar_specs command

usage: iw <phy> set sar_specs <sar type> <range index:sar power>*
e.g.
iw phy0 set sar_specs 0 0:100 1:90 2:80...
where sar type should correspond to wiphy's sar_capa,
and range index should be valid in wiphy's sar_capa.

For now, kernel sar type supports only 0 (NL80211_SAR_TYPE_POWER)
which means that the sar power limitation is specified in 0.25dBm unit.

Cc: Carl Huang <cjhuang@codeaurora.org>
Signed-off-by: Zong-Zhe Yang <kevin_yang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://lore.kernel.org/r/20211007085615.40399-1-pkshih@realtek.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>