[UWB HAL] Use AsyncFd to read the buffer only when it's readable.

This CL fixes the issue that some bytes are missing after we toggle uwb
off and on.

Test: atest CtsUwbTestCases
Bug: 302005209

Change-Id: I8ad8072fe01c8d1f466d8debf0ccf5831b3eddf8
diff --git a/uwb/aidl/default/Android.bp b/uwb/aidl/default/Android.bp
index c6d1a52..2b7ef57 100644
--- a/uwb/aidl/default/Android.bp
+++ b/uwb/aidl/default/Android.bp
@@ -20,6 +20,7 @@
         "libbinder_rs",
         "libbinder_tokio_rs",
         "libtokio",
+        "libtokio_util",
         "libnix",
         "libanyhow",
     ],