runtime: remove unused __vdso_time_sym

It's unused since https://golang.org/cl/99320043

Change-Id: I74d69ff894aa2fb556f1c2083406c118c559d91b
Reviewed-on: https://go-review.googlesource.com/98195
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/runtime/vdso_linux_amd64.go

@@ -11,14 +11,12 @@ const (
 )
 
 var sym_keys = []symbol_key{
-	{"__vdso_time", 0xa33c485, 0x821e8e0d, &__vdso_time_sym},
 	{"__vdso_gettimeofday", 0x315ca59, 0xb01bca00, &__vdso_gettimeofday_sym},
 	{"__vdso_clock_gettime", 0xd35ec75, 0x6e43a318, &__vdso_clock_gettime_sym},
 }
 
 // initialize with vsyscall fallbacks
 var (
-	__vdso_time_sym          uintptr = 0xffffffffff600400
 	__vdso_gettimeofday_sym  uintptr = 0xffffffffff600000
 	__vdso_clock_gettime_sym uintptr = 0
 )