Revert "msl: Use a struct for threadgroup memory arguments"

This reverts commit af8cd3b7f5.

Reason for revert: breaking roll into Dawn.

Original change's description:
> msl: Use a struct for threadgroup memory arguments
>
> MSL has a limit on the number of threadgroup memory arguments, so use
> a struct to support an arbitrary number of workgroup variables.
>
> Bug: tint:938
> Change-Id: I40e4a8d99bc4ae074010479a56e13e2e0acdded3
> Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/64380
> Kokoro: Kokoro <noreply+kokoro@google.com>
> Auto-Submit: James Price <jrprice@google.com>
> Reviewed-by: Ben Clayton <bclayton@google.com>
> Commit-Queue: James Price <jrprice@google.com>

TBR=bclayton@google.com,jrprice@google.com,noreply+kokoro@google.com,tint-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: I58a07c4ab7e92bda205e2bbbab41e0b347aeb1e8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: tint:938
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/65162
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Kokoro: Corentin Wallez <cwallez@chromium.org>

src/resolver/resolver.cc

@@ -2659,10 +2659,7 @@ bool Resolver::ValidateFunctionCall(const ast::CallExpression* call,
         }
       }
 
-      if (!is_valid &&
-          IsValidationEnabled(
-              param->declaration->decorations(),
-              ast::DisabledValidation::kIgnoreInvalidPointerArgument)) {
+      if (!is_valid) {
         AddError(
             "expected an address-of expression of a variable identifier "
             "expression or a function parameter",