livepatch: Add "replace" sysfs attribute

livepatch: Add "replace" sysfs attribute

There are situations when it might make sense to combine livepatches
with and without the atomic replace on the same system. For example,
the livepatch without the atomic replace might provide a hotfix
or extra tuning.

Managing livepatches on such systems might be challenging. And the
information which of the installed livepatches do not use the atomic
replace would be useful.

Add new sysfs interface 'replace'. It works as follows:

   $ cat /sys/kernel/livepatch/livepatch-non_replace/replace
   0

   $ cat /sys/kernel/livepatch/livepatch-replace/replace
   1

[ commit log improved by Petr ]

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lore.kernel.org/r/20240625151123.2750-2-laoar.shao@gmail.com
Signed-off-by: Petr Mladek <pmladek@suse.com>