Remove libbase header export from libhidltransport

It's not used in any header.

Test: build (nothing complains)
Change-Id: If1721aaaae149fcadaa9d7869040594ae18c61f6
diff --git a/transport/Android.bp b/transport/Android.bp
index 77cfe27..5b0c11c 100644
--- a/transport/Android.bp
+++ b/transport/Android.bp
@@ -38,7 +38,6 @@
         "libvndksupport",
     ],
     export_shared_lib_headers: [
-        "libbase",
         "libutils",
         "libhidlbase",
     ],