doc/vm/page_owner.rst: remove content related to -c option

-c option has been removed from page_owner_sort.c.

Remove the usage of -c option from Documentation.

This work is coauthored by
        Shenghong Han
        Yixuan Cao
        Chongxi Zhao
        Jiajian Ye
        Yuhong Feng
        Yongqiang Liu

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Yinan Zhang <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Sean Anderson <[email protected]>
Cc: Tang Bin <[email protected]>
Cc: Zhenliang Wei <[email protected]>
Cc: Georgi Djakov <[email protected]>
Cc: Chongxi Zhao <[email protected]>
Cc: Jiajian Ye <[email protected]>
Cc: Yixuan Cao <[email protected]>
Cc: Yuhong Feng <[email protected]>
Cc: Yongqiang Liu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Documentation/vm/page_owner.rst

@@ -125,7 +125,6 @@ Usage
    additional function:
 
 	Cull:
-		-c		Cull by comparing stacktrace instead of total block.
 		--cull <rules>
 				Specify culling rules.Culling syntax is key[,key[,...]].Choose a
 				multi-letter key from the **STANDARD FORMAT SPECIFIERS** section.