mm/damon: remove DAMON debugfs interface

It's time to remove DAMON debugfs interface, which has deprecated long
before in February 2023.  Read the cover letter of this patch series for
more details.

All documents and related tests are also removed.  Finally remove the
interface.

Link: https://lkml.kernel.org/r/20250106191941.107070-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Hu Haowen <2023002089@link.tyut.edu.cn>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Rae Moar <rmoar@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yanteng Si <si.yanteng@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/Kconfig

@@ -71,24 +71,6 @@ config DAMON_SYSFS_KUNIT_TEST
 
 	  If unsure, say N.
 
-config DAMON_DBGFS_DEPRECATED
-	bool "DAMON debugfs interface (DEPRECATED!)"
-	depends on DAMON_VADDR && DAMON_PADDR && DEBUG_FS
-	help
-	  This builds the debugfs interface for DAMON.  The user space admins
-	  can use the interface for arbitrary data access monitoring.
-
-	  If unsure, say N.
-
-	  This is deprecated, so users should move to the sysfs interface
-	  (DAMON_SYSFS).  If you depend on this and cannot move, please report
-	  your usecase to damon@lists.linux.dev and linux-mm@kvack.org.
-
-config DAMON_DBGFS
-	bool
-	default y
-	depends on DAMON_DBGFS_DEPRECATED
-
 config DAMON_RECLAIM
 	bool "Build DAMON-based reclaim (DAMON_RECLAIM)"
 	depends on DAMON_PADDR

mm/damon/Makefile

@@ -4,6 +4,5 @@ obj-y				:= core.o
 obj-$(CONFIG_DAMON_VADDR)	+= ops-common.o vaddr.o
 obj-$(CONFIG_DAMON_PADDR)	+= ops-common.o paddr.o
 obj-$(CONFIG_DAMON_SYSFS)	+= sysfs-common.o sysfs-schemes.o sysfs.o
-obj-$(CONFIG_DAMON_DBGFS)	+= dbgfs.o
 obj-$(CONFIG_DAMON_RECLAIM)	+= modules-common.o reclaim.o
 obj-$(CONFIG_DAMON_LRU_SORT)	+= modules-common.o lru_sort.o