LU-18821 build: fix [-Werror=pointer-to-int-cast] error

LU-18821 build: fix [-Werror=pointer-to-int-cast] error

This patch fixes the following error on 32-bit architectures
by replacing the __u64 cast with uintptr_t, which is either
32-bit or 64-bit:

  lustre/include/obd_class.h: In function 'obd_quota_iter':
  lustre/include/obd_class.h:1289:39: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
   1289 |                 oqctl->qc_iter_list = (__u64)list;
        |                                       ^
  cc1: all warnings being treated as errors

Change-Id: I5938a4c09a50010ce3b99bc6f978fed5cc32a5d6
Signed-off-by: Jian Yu <yujian@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58440
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Hongchao Zhang <hongchao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>