Add HAL APIs for TX power limits

To lower the instantaneous battery current draw of WiFi, we provide
a way to allow PowerManager to enable/disable Tx power limits.
In the legacy HAL, we call the API in Broadcom HAL to
enable/disable WiFi TX power limits.

Bug: 215193418
Test: New APIs work fine
Change-Id: I1fbe71c3380514e2eba96adc5902d2028a55e006