Revert D31861962: [qnnpack] Remove redundant fp16 dependency
Test Plan: revert-hammer
Differential Revision:
D31861962 (https://github.com/pytorch/pytorch/commit/4061239fdd42c281108c05639e8b5bf49c42e36c)
Original commit changeset: e1425c7dc3e6
fbshipit-source-id: 418f8173c19b9541316443e1ab4ec39062561b5e
