bpf: Add missing access_ok call to copy_user_syms

In the Linux kernel, the following vulnerability has been resolved: bpf: Add missing access_ok call to copy_user_syms As reported by sashiko we use __get_user without prior access_ok call on the user space pointer. Adding the missing call for the whole pointer array. Plus removing the err check in the error path, because it's not needed and also we can return -ENOMEM directly from the first kvmalloc_array fail path. [1] https://lore.kernel.org/bpf/20260611115503.AC16D1F00893@smtp.kernel.org/