simplify f16 to_degrees and to_radians by using expression directly

Author: karolzwolak

library/core/src/num/f16.rs

@@ -640,9 +640,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_degrees(self) -> Self {
-        // Use a literal for better precision.
-        const PIS_IN_180: f16 = 57.2957795130823208767981548141051703_f16;
-        self * PIS_IN_180
+        self * 57.2957795130823208767981548141051703_f16
     }
 
     /// Converts degrees to radians.
@@ -663,9 +661,7 @@ impl f16 {
     #[unstable(feature = "f16", issue = "116909")]
     #[must_use = "this returns the result of the operation, without modifying the original"]
     pub const fn to_radians(self) -> f16 {
-        // Use a literal for better precision.
-        const RADS_PER_DEG: f16 = 0.017453292519943295769236907684886_f16;
-        self * RADS_PER_DEG
+        self * 0.017453292519943295769236907684886_f16
     }
 
     /// Returns the maximum of the two numbers, ignoring NaN.