RFR: 8262235: Remove unnecessary logic in hugetlbfs_sanity_check()

[Stefan Johansson]

Please review this change that removes some additional verification not really needed when doing the sanity check for hugetlbfs-pages.

**Summary**
The call to `mmap` in `hugetlbfs_sanity_check()` will only succeed if it can satisfy the mapping using large pages. If this was not the case, we would have to double check all large page mappings not just this sanity check. So the reading of `/proc/self/maps` is safe to remove.

**Testing**
Sanity run through mach 5 and local testing with and without large pages configured.

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Commit messages:
 - 8262235: Remove unnecessary logic in hugetlbfs_sanity_check()

Changes: https://git.openjdk.java.net/jdk/pull/3048/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3048&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262235
  Stats: 24 lines in 1 file changed: 1 ins; 19 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3048.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3048/head:pull/3048

PR: https://git.openjdk.java.net/jdk/pull/3048