mm/hugetlb.c: remove unnecessary initialization of local `err'

Link: https://lkml.kernel.org/r/20220905020918.3552-1-zeming@nfschina.com


Signed-off-by: Li zeming <zeming@nfschina.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>