mm: replace hpage_nr_pages with thp_nr_pages

mm: replace hpage_nr_pages with thp_nr_pages

The thp prefix is more frequently used than hpage and we should be
consistent between the various functions.

[[email protected]: fix mm/migrate.c]

Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: William Kucharski <[email protected]>
Reviewed-by: Zi Yan <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>