[lld] [lld][ELF] removed peek2 in linker script lexer (PR #99539)

[Hongyu Chen via llvm-commits]

yugier wrote:

> We should not add the peek2 ability to `peek`. Instead, the call site should check whether the first token is `(`, and if yes, peek another token to check `NOLOAD/COPY/INFO/TYPE`. Basically, we move some `"("` code from `readSectionDirective` to the caller.

I wanted to do this but it seems like once `isDirective == false` we need call `readExpr` and `readExpr` calls `readPrimary` . If we consume `(` forreadSectionDirective then we might have to change `readExpr` and `readPrimary`. 

https://github.com/llvm/llvm-project/pull/99539