Revert D35258695: [quant][fx] Cleanup unused to_fp16 check code in lowering
Test Plan: revert-hammer
Differential Revision:
D35258695 (https://github.com/pytorch/pytorch/commit/ec6f7670978abbe46603c00b5950cbac13923061)
Original commit changeset: 2297696493fe
Original Phabricator Diff: D35258695 (https://github.com/pytorch/pytorch/commit/ec6f7670978abbe46603c00b5950cbac13923061)
fbshipit-source-id: 8c2d608f3c585b8c00275f64a82478cb1af25b50
(cherry picked from commit b0b5f4f3e3414cb538ab35bc2968d39408157c7b)
