qcacmn: Add QCA vendor interface to fetch thermal stats from driver

Enhance QCA_NL80211_VENDOR_SUBCMD_THERMAL_CMD to fetch thermal stats
for different temperature levels from the driver to userspace. The
stats will be stored in the driver/firmware for predefined temperature
levels and will be reported to userspace when
QCA_NL80211_VENDOR_SUBCMD_THERMAL_CMD is sent with command type
QCA_WLAN_VENDOR_ATTR_THERMAL_CMD_TYPE_GET_THERMAL_STATS.
The thermal stats can be cleared from userspace by sending
QCA_NL80211_VENDOR_SUBCMD_THERMAL_CMD command with type
QCA_WLAN_VENDOR_ATTR_THERMAL_CMD_TYPE_CLEAR_THERMAL_STATS.

Change-Id: I937bc89865df484a068c887d906df5a9502f1925
CRs-Fixed: 3016851