selftests/damon: fix selftests by installing drgn related script

drgn_dump_damon_status is not installed during kselftest setup.  It can
break other tests which depend on drgn_dump_damon_status.  Install
drgn_dump_damon_status files to fix broken test.

Link: https://lkml.kernel.org/r/20250812140046.660486-1-ekffu200098@gmail.com
Fixes: f3e8e1e ("selftests/damon: add drgn script for extracting damon status")
Signed-off-by: Sang-Heon Jeon <ekffu200098@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: hqsz

tools/testing/selftests/damon/Makefile

@@ -4,6 +4,7 @@
 TEST_GEN_FILES += access_memory access_memory_even
 
 TEST_FILES = _damon_sysfs.py
+TEST_FILES += drgn_dump_damon_status.py
 
 # functionality tests
 TEST_PROGS += sysfs.sh