selftests/mm: link vm_util.c always

We do have plenty of files that want to link against vm_util.c.  Just make
it simple by linking it always.

Link: https://lkml.kernel.org/r/20230412164220.328123-1-peterx@redhat.comSigned-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/mm/Makefile

@@ -106,18 +106,7 @@ TEST_FILES += va_128TBswitch.sh
 
 include ../lib.mk
 
-$(OUTPUT)/cow: vm_util.c
-$(OUTPUT)/khugepaged: vm_util.c
-$(OUTPUT)/ksm_functional_tests: vm_util.c
-$(OUTPUT)/madv_populate: vm_util.c
-$(OUTPUT)/mkdirty: vm_util.c
-$(OUTPUT)/soft-dirty: vm_util.c
-$(OUTPUT)/split_huge_page_test: vm_util.c
-$(OUTPUT)/userfaultfd: vm_util.c
-$(OUTPUT)/gup_test: vm_util.c
-$(OUTPUT)/mrelease_test: vm_util.c
-$(OUTPUT)/transhuge-stress: vm_util.c
-$(OUTPUT)/ksm_tests: vm_util.c
+$(TEST_GEN_PROGS): vm_util.c
 
 ifeq ($(MACHINE),x86_64)
 BINARIES_32 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_32))