remove fp16 target feature from some vreinterpret intrinsics

[usamoi]

Usage of them is accepted by clang without fullfp16 (https://godbolt.org/z/dhffa4YT9). It seems that they are missing in #1978.

cc @adamgemmell, in case I misunderstood

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[adamgemmell]

Looks good to me, thank you!