Rollup merge of rust-lang#141893 - usamoi:lossless, r=tgross35

remove `f16: From<u16>`

it's not a lossless conversion

r? ``@tgross35``

Author: matthiaskrgr

library/core/src/convert/num.rs

@@ -175,7 +175,6 @@ impl_from!(u8 => f16, #[stable(feature = "lossless_float_conv", since = "1.6.0")
 impl_from!(u8 => f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u8 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u8 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
-impl_from!(u16 => f16, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u16 => f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u16 => f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);
 impl_from!(u16 => f128, #[stable(feature = "lossless_float_conv", since = "1.6.0")]);