qcacmn: QCA vendor command for getting STA information

Add a QCA vendor subcommand QCA_NL80211_VENDOR_SUBCMD_GET_STA_INFO with
attributes defined in qca_wlan_vendor_attr_get_sta to get information
for BSS in STA mode or for peer STAs in AP mode. This vendor sub command
can be used to get STA information from driver to userspace.
The attributes defined in enum qca_wlan_vendor_attr_get_sta_info
are used to encapsulate required information.

Change-Id: I9747516de377a2be23cca6023f2e92f014e42ac2
CRs-Fixed: 2591613