smb/client: replace nt_errs with ntstatus_to_dos_map

smb/client: replace nt_errs with ntstatus_to_dos_map

The ntstatus_to_dos_map[] array now contains the NT error strings,
making the nt_errs[] array redundant.

Introduce `struct ntstatus_to_dos_err` instead of an anonymous struct.
This allows cifs_print_status() to look up error strings directly
from a single table.

Remove nterr.c, as nt_errs[] was its only functional content.

Signed-off-by: Huiwen He <hehuiwen@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>