ANDROID: delete tool added by mistake

Remove the gen-hyprel binary added accidentally while backporting a
patch into an older branch. The tool gets generated in newer builds and
wasn't part of the gitignore file here.

Fixes: d04d0acd ("BACKPORT: FROMGIT: binder: frozen notification")
Change-Id: I103358cb2ca9c5fb934f047033e44c04fe85298d
Signed-off-by: Carlos Llamas <cmllamas@google.com>