mm/THP: add pmd args to pgtable deposit and withdraw APIs

mm/THP: add pmd args to pgtable deposit and withdraw APIs

This will be later used by powerpc THP support.  In powerpc we want to use
pgtable for storing the hash index values.  So instead of adding them to
mm_context list, we would like to store them in the second half of pmd

Signed-off-by: Aneesh Kumar K.V <[email protected]>
Reviewed-by: Andrea Arcangeli <[email protected]>
Reviewed-by: David Gibson <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Benjamin Herrenschmidt <[email protected]>