selftests: memfd: split regular and hugetlbfs tests

Split normal memfd and hugetlbfs tests to improve the test reporting.
Remove run_fuse_test.sh and memfd_test from run_tests.sh and add them
to the Makefile.

Add memfd_test to TEST_GEN_PROGS to be run separately.
Rename run_tests.sh to run_hugetlbfs_test.sh
Add run_fuse_test.sh and run_hugetlbfs_test.sh to TEST_PROGS

The report for non-root run wth this change is:

TAP version 13
selftests: memfd: memfd_test
========================================
memfd: CREATE
memfd: BASIC
memfd: SEAL-WRITE
memfd: SEAL-SHRINK
memfd: SEAL-GROW
memfd: SEAL-RESIZE
memfd: SHARE-DUP
memfd: SHARE-MMAP
memfd: SHARE-OPEN
memfd: SHARE-FORK
memfd: SHARE-DUP (shared file-table)
memfd: SHARE-MMAP (shared file-table)
memfd: SHARE-OPEN (shared file-table)
memfd: SHARE-FORK (shared file-table)
memfd: DONE
ok 1..1 selftests: memfd: memfd_test [PASS]
selftests: memfd: run_fuse_test.sh
========================================
opening: ./mnt/memfd
fuse: DONE
ok 1..2 selftests: memfd: run_fuse_test.sh [PASS]
selftests: memfd: run_hugetlbfs_test.sh
========================================
Please run memfd with hugetlbfs test as root
not ok 1..3 selftests: memfd: run_hugetlbfs_test.sh [SKIP]

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>