WiFi-Hal: Map wifi_latency_mode to QCA vendor latency level

This maps framework's latency mode to QCA vendor latency level:
- WIFI_LATENCY_MODE_NORMAL: QCA...LATENCY...NORMAL
- WIFI_LATENCY_MODE_LOW   : QCA...LATENCY...ULTRA_LOW

For other unsupported modes, resetting to QCA...LATENCY...NORMAL

CRs-Fixed: 2441730
Change-Id: I809409b32f32545820dbc505002a074f28a5a412