meta-qti-wlan: Add iperf to image

The iperf tool is needed to do the performance test. Add
this tool in sdxprairie image.

Change-Id: I6edf0bc44cb45156d9bfc1b38c9e888e94a1709e
CRs-Fixed: 2480905

recipes-products/images/sdxprairie/sdxprairie-wlan-image.inc

@@ -3,3 +3,4 @@ IMAGE_INSTALL += "hostap-daemon-qcacld"
 IMAGE_INSTALL += "qcacld32-ll-hasting"
 IMAGE_INSTALL += "wpa-supplicant-qcacld"
 IMAGE_INSTALL += "wlan-sigma-dut"
+IMAGE_INSTALL += "iperf"