mm/hugetlb: remove unused local variable dst_entry in copy_hugetlb_page_range()

mm/hugetlb: remove unused local variable dst_entry in copy_hugetlb_page_range()

Commit a0e4f7b82610 ("mm/hugetlb: make detecting shared pte more
reliable") modifies copy_hugetlb_page_range() such that
huge_ptep_get(dst_pte) and the local variable dst_entry is not used
explicitly in this function.

Remove this unused local variable dst_entry in copy_hugetlb_page_range().
No functional change.

Link: https://lkml.kernel.org/r/20220822082525.26071-1-lukas.bulwahn@gmail.com
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>