[wlantest] Remove leftover iotxn methods

They were disabled by the preprocessor anyway.

Change-Id: Ifb00beb1a1d61de2c67b5c7c10859e67cda52766
diff --git a/drivers/wlan/testing/iface-device.cpp b/drivers/wlan/testing/iface-device.cpp
index 13ede1d..3f60cf2 100644
--- a/drivers/wlan/testing/iface-device.cpp
+++ b/drivers/wlan/testing/iface-device.cpp
@@ -22,9 +22,6 @@
     .release = [](void* ctx) { DEV(ctx)->Release(); },
     .read = nullptr,
     .write = nullptr,
-#if DDK_WITH_IOTXN
-    .iotxn_queue = nullptr,
-#endif
     .get_size = nullptr,
     .ioctl = nullptr,
     .suspend = nullptr,
diff --git a/drivers/wlan/testing/phy-device.cpp b/drivers/wlan/testing/phy-device.cpp
index 900e240..fa1e338 100644
--- a/drivers/wlan/testing/phy-device.cpp
+++ b/drivers/wlan/testing/phy-device.cpp
@@ -29,9 +29,6 @@
     .release = [](void* ctx) { DEV(ctx)->Release(); },
     .read = nullptr,
     .write = nullptr,
-#if DDK_WITH_IOTXN
-    .iotxn_queue = nullptr,
-#endif
     .get_size = nullptr,
     .ioctl = [](void* ctx, uint32_t op, const void* in_buf, size_t in_len, void* out_buf,
                 size_t out_len, size_t* out_actual) -> zx_status_t {