livepatch: Add comment to clarify klp_add_nops()

Add detailed comments to clarify the purpose of klp_add_nops() function.
These comments are based on Petr's explanation[0].

Link: https://lore.kernel.org/all/Z6XUA7D0eU_YDMVp@pathway.suse.cz/ [0]
Suggested-by: Petr Mladek <pmladek@suse.com>
Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20250227024733.16989-2-laoar.shao@gmail.com
Signed-off-by: Petr Mladek <pmladek@suse.com>

Author: laoar

kernel/livepatch/core.c

@@ -601,9 +601,12 @@ static int klp_add_object_nops(struct klp_patch *patch,
 }
 
 /*
- * Add 'nop' functions which simply return to the caller to run
- * the original function. The 'nop' functions are added to a
- * patch to facilitate a 'replace' mode.
+ * Add 'nop' functions which simply return to the caller to run the
+ * original function.
+ *
+ * They are added only when the atomic replace mode is used and only for
+ * functions which are currently livepatched but are no longer included
+ * in the new livepatch.
  */
 static int klp_add_nops(struct klp_patch *patch)
 {