compiler: remove medium code model workaround for loongarch64

The default was changed in LLVM 21.

Author: alexrp

src/Package/Module.zig

@@ -237,11 +237,7 @@ pub fn create(arena: Allocator, options: CreateOptions) !*Package.Module {
     const code_model: std.builtin.CodeModel = b: {
         if (options.inherited.code_model) |x| break :b x;
         if (options.parent) |p| break :b p.code_model;
-        break :b switch (target.cpu.arch) {
-            // Temporary workaround until LLVM 21: https://github.com/llvm/llvm-project/pull/132173
-            .loongarch64 => .medium,
-            else => .default,
-        };
+        break :b .default;
     };
 
     const is_safe_mode = switch (optimize_mode) {