wifi: ath11k: Fix qmi_msg_handler data structure initialization

In the Linux kernel, the following vulnerability has been resolved: wifi: ath11k: Fix qmi_msg_handler data structure initialization qmi_msg_handler is required to be null terminated by QMI module. There might be a case where a handler for a msg id is not present in the handlers array which can lead to infinite loop while searching the handler and therefore out of bound access in qmi_invoke_handler(). Hence update the initialization in qmi_msg_handler data structure. Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.5.0.1-01100-QCAHKSWPL_SILICONZ-1