For QCA_LL_LEGACY_TX_FLOW_CONTROL data flow control, currently it cannot support TX off for thermal mgmt. Similar to thermal implementation in FW, refine ol_tx_set_throttle_phase_time() to support thermal mitigation TX off processing when INI throttle duty cycle set to maximum 100. Change-Id: I208288bda2ad7ca1a14be0b80a0d57361ce0ec8c CRs-Fixed: 3413545