ExternalCameraHAL: Prevent memory leak when manipulating native_handle

native_handle objects created by makeFromAidl need to be deleted
with native_handle_delete. Not doing so leads to a memory leak
every time makeFromAidl is called.

This CL ensures that native_handle_delete is called on the
return value of makeFromAidl wherever it is used.

Bug: 305638723
Test: n/a. No functional change.
Change-Id: Ia99ba6e3abbdf7dec75383450a60c944b92a9c74