webnn: remove softplus parameter steepness
Remove this parameter since it's no longer in the spec.
Bug: 40206287
Change-Id: Ibcf4b3a7bcda8fc5ba3588667449d46a690b65c3
Cq-Include-Trybots: luci.chromium.try:win11-blink-rel
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5486742
Commit-Queue: Shiyi Zou shiyi.zou@intel.com
Auto-Submit: Shiyi Zou shiyi.zou@intel.com
Reviewed-by: Alex Gough ajgo@chromium.org
Reviewed-by: ningxin hu ningxin.hu@intel.com
Reviewed-by: Austin Sullivan asully@chromium.org
Cr-Commit-Position: refs/heads/main@{#1293444}