This reverts commit 2da05dfc.

Reason for revert: Will need to commit some of the changes as a port of  46648402

Original change's description:
> PPC/s390: [codegen] Removed ParameterCount class
> 
> Port 1e696896
> 
> Original Commit Message:
> 
>     It was used only with Register inputs, so we can replace its uses with
>     the Registers themselves.
> 
> R=​solanes@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
> BUG=
> LOG=N
> 
> Change-Id: I95c0e6fc19ea5f9579d022756a4693ea0140d2f7
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1890543
> Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
> Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
> Cr-Commit-Position: refs/heads/master@{#64661}

TBR=michael_dawson@ca.ibm.com,jyan@ca.ibm.com,joransiu@ca.ibm.com,miladfar@ca.ibm.com,solanes@chromium.org

Change-Id: I10f0a7f3c81f7c5c396df1e26ead50c5f8755231
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1891073Reviewed-by: Milad Farazmand <miladfar@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#64662}