BACKPORT: mm: simplify thp_vma_allowable_order

Combine the three boolean arguments into one flags argument for
readability.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit e0ffb29b)
[ Fix trivial conflict in khugpaged.c and huge_mm.h
   - Kalesh Singh ]
Bug: 313807618
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Change-Id: Ibfcef68b11da329c1dd6a0cfd0078fc77fac39ec