wifi(implementation): Remove support for STA + STA in chip combination

Not planning to support STA + STA in Pixel 2018, so remove support for
it from the chip combination.

Also, fixed an error in existing unit tests (Need to mock
WifiLegacyHal.registerRadioModeChangeCallbackHandler)

Bug: 74079118
Test: Tested STA connection & AP bringup on taimen.
Test: ./hardware/interfaces/wifi/1.2/default/tests/runtests.sh
Change-Id: I996e63ecdda4d6a5a07a40d5f7ed1072ada37597
diff --git a/wifi/1.2/default/wifi_chip.cpp b/wifi/1.2/default/wifi_chip.cpp
index 201b8e4..dcd0a3c 100644
--- a/wifi/1.2/default/wifi_chip.cpp
+++ b/wifi/1.2/default/wifi_chip.cpp
@@ -1171,7 +1171,7 @@
     // (conditional on isDualInterfaceSupported()):
     //    Interface Combination 1: Will support 1 STA and 1 P2P or NAN(optional)
     //                             concurrent iface operations.
-    //    Interface Combination 2: Will support 1 STA and 1 STA or AP concurrent
+    //    Interface Combination 2: Will support 1 STA and 1 AP concurrent
     //                             iface operations.
     // If Aware is enabled (conditional on isAwareSupported()), the iface
     // combination will be modified to support either P2P or NAN in place of
@@ -1181,8 +1181,7 @@
         const IWifiChip::ChipIfaceCombinationLimit
             chip_iface_combination_limit_1 = {{IfaceType::STA}, 1};
         const IWifiChip::ChipIfaceCombinationLimit
-            chip_iface_combination_limit_2 = {{IfaceType::STA, IfaceType::AP},
-                                              1};
+            chip_iface_combination_limit_2 = {{IfaceType::AP}, 1};
         IWifiChip::ChipIfaceCombinationLimit chip_iface_combination_limit_3;
         if (feature_flags_.lock()->isAwareSupported()) {
             chip_iface_combination_limit_3 = {{IfaceType::P2P, IfaceType::NAN},