time: remove redundant uint32 conversion in split

cd is a uint32 converted again.

Change-Id: Ia41e247e0644c17cd9e0593d79457db77512fc3e
GitHub-Last-Rev: 1ba8596
GitHub-Pull-Request: #74679
Reviewed-on: https://go-review.googlesource.com/c/go/+/689055
Auto-Submit: Jorropo <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: Jorropo <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

Author: cxbdasheng

src/time/time.go

@@ -667,7 +667,7 @@ func (days absDays) split() (century absCentury, cyear absCyear, ayday absYday)
 	// so do that instead, saving a few cycles.
 	// See Neri and Schneider, section 8.3
 	// for more about this optimization.
-	hi, lo := bits.Mul32(2939745, uint32(cd))
+	hi, lo := bits.Mul32(2939745, cd)
 	cyear = absCyear(hi)
 	ayday = absYday(lo / 2939745 / 4)
 	return