runtime: fix usleep on windows/arm

runtime: fix usleep on windows/arm

Changed calling convention to pre-multiply the argument by -100,
and then deleted the * 100 but not the negation in the windows/arm assembly.
Delete the negation.

Fixes the current all.bash breakage on windows/arm builder.
(Maybe that will uncover more.)

Change-Id: I13006a44866ecc007586deb180a49c038d70aa99
Reviewed-on: https://go-review.googlesource.com/c/go/+/295529
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>