mm: introduce compound_nr()

Replace 1 << compound_order(page) with compound_nr(page).  Minor
improvements in readability.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Cc: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
18 files changed