Fix deref_to_depth loop type check to use cur_type

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: r41k0u

pythonbpf/expr/ir_ops.py

@@ -11,7 +11,7 @@ def deref_to_depth(func, builder, val, target_depth):
     cur_type = val.type
 
     for depth in range(target_depth):
-        if not isinstance(val.type, ir.PointerType):
+        if not isinstance(cur_type, ir.PointerType):
             logger.error("Cannot dereference further, non-pointer type")
             return None