selftests: vm: install test_vmalloc.sh for run_vmtests

Add test_vmalloc.sh to TEST_FILES to make sure it gets installed for
run_vmtests.

Fixed below error:
./run_vmtests: line 217: ./test_vmalloc.sh: No such file or directory

Tested with: make TARGETS=vm install INSTALL_PATH=$PWD/x
Signed-off-by: NNaresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: NShuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/vm/Makefile

@@ -25,6 +25,8 @@ TEST_GEN_FILES += virtual_address_range
 
 TEST_PROGS := run_vmtests
 
+TEST_FILES := test_vmalloc.sh
+
 KSFT_KHDR_INSTALL := 1
 include ../lib.mk