Solve build errors on kernel 6.9 and higher

[yizeyi18]

In kernel commit 902861e34c401696ed9ad17a54c8790e7e8e3069, `pmd_large` and
`pud_large` was renamed to `pmd_leaf` and `pud_leaf` by patch from redhat.

This patch applies this change to xpmem.

Symbols for PowerPC was also renamed in the same kernel commit. As
author of this patch knows none about the reason of redirecting `pud_is_large`
to something other than `pud_large`, the PPC part is unchanged.