audiohal: Fix handling of invalid arguments in 'debugDump' methods

Add checks for validity of the passed in native handle.

Bug: 37590777
Change-Id: If906f0086c3442819e1844cc521215d5b74af015
Test: VTS
diff --git a/audio/effect/2.0/default/EffectsFactory.cpp b/audio/effect/2.0/default/EffectsFactory.cpp
index 08d92bd..922a922 100644
--- a/audio/effect/2.0/default/EffectsFactory.cpp
+++ b/audio/effect/2.0/default/EffectsFactory.cpp
@@ -186,7 +186,7 @@
 }
 
 Return<void> EffectsFactory::debugDump(const hidl_handle& fd)  {
-    if (fd->numFds == 1) {
+    if (fd.getNativeHandle() != nullptr && fd->numFds == 1) {
         EffectDumpEffects(fd->data[0]);
     }
     return Void();