Implement vcmla_lane with ARM intrinsics

[sayantn]

Also corrects a small typo in gen-arm (all changes are verified with the new intrinsic-test and GCC, clang is buggy for the f16 intrinsics)

[rustbot]

r? @Amanieu

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• Owners of files modified in this PR: @Amanieu, @adamgemmell, @davidtwco, @folkertdev, @sayantn
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