bpf: selftests: Fix bpf_iter_task_vma_new() prototype

bpf_iter_task_vma_new() is defined as taking a u64 as its 3rd argument.
u64 is a unsigned long long. bpf_experimental.h was defining the
prototype as unsigned long.

Fix by using __u64.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/fab4509bfee914f539166a91c3ff41e949f3df30.1718207789.git.dxu@dxuuu.xyzSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/bpf_experimental.h

@@ -163,7 +163,7 @@ struct bpf_iter_task_vma;
 
 extern int bpf_iter_task_vma_new(struct bpf_iter_task_vma *it,
 				 struct task_struct *task,
-				 unsigned long addr) __ksym;
+				 __u64 addr) __ksym;
 extern struct vm_area_struct *bpf_iter_task_vma_next(struct bpf_iter_task_vma *it) __ksym;
 extern void bpf_iter_task_vma_destroy(struct bpf_iter_task_vma *it) __ksym;