bpf: Remove migrate_{disable|enable} from bpf_local_storage_free()

bpf: Remove migrate_{disable|enable} from bpf_local_storage_free()

bpf_local_storage_free() has three callers:

1) bpf_local_storage_alloc()
Its caller must have disabled migration.

2) bpf_local_storage_destroy()
Its four callers (bpf_{cgrp|inode|task|sk}_storage_free()) have already
invoked migrate_disable() before invoking bpf_local_storage_destroy().

3) bpf_selem_unlink()
Its callers include: cgrp/inode/task/sk storage ->map_delete_elem
callbacks, bpf_{cgrp|inode|task|sk}_storage_delete() helpers and
bpf_local_storage_map_free(). All of these callers have already disabled
migration before invoking bpf_selem_unlink().

Therefore, it is OK to remove migrate_{disable|enable} pair from
bpf_local_storage_free().

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250108010728.207536-16-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>