mm: memory-failure: convert to pr_fmt()

mm: memory-failure: convert to pr_fmt()

Use pr_fmt to prefix all pr_<level> output, but unpoison_memory() and
soft_offline_page() are used by error injection, which have own prefixes
like "Unpoison:" and "soft offline:", meanwhile, soft_offline_page() could
be used by memory hotremove, so reset pr_fmt before unpoison_pr_info
definition to keep the original output for them.

[[email protected]: v3]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: Naoya Horiguchi <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>