runtime: remove unused g parameter

Found by github.com/mvdan/unparam.

Change-Id: I20145440ff1bcd27fcf15a740354c52f313e536c
Reviewed-on: https://go-review.googlesource.com/37894
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

src/runtime/proc.go

@@ -2252,7 +2252,7 @@ func park_m(gp *g) {
 	_g_ := getg()
 
 	if trace.enabled {
-		traceGoPark(_g_.m.waittraceev, _g_.m.waittraceskip, gp)
+		traceGoPark(_g_.m.waittraceev, _g_.m.waittraceskip)
 	}
 
 	casgstatus(gp, _Grunning, _Gwaiting)

src/runtime/trace.go

@@ -982,7 +982,7 @@ func traceGoPreempt() {
 	traceEvent(traceEvGoPreempt, 1)
 }
 
-func traceGoPark(traceEv byte, skip int, gp *g) {
+func traceGoPark(traceEv byte, skip int) {
 	if traceEv&traceFutileWakeup != 0 {
 		traceEvent(traceEvFutileWakeup, -1)
 	}