selftests/vm: cleanup hugetlb file after mremap test

selftests/vm: cleanup hugetlb file after mremap test

The hugepage-mremap test will create a file in a hugetlb filesystem.  In a
default 'run_vmtests' run, the file will contain all the hugetlb pages.
After the test, the file remains and there are no free hugetlb pages for
subsequent tests.  This causes those hugetlb tests to fail.

Change hugepage-mremap to take the name of the hugetlb file as an
argument.  Unlink the file within the test, and just to be sure remove the
file in the run_vmtests script.

Link: https://lkml.kernel.org/r/20220201033459.156944-1-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mina Almasry <almasrymina@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>