ksmbd: fix corrupted mtime and ctime in smb2_open

ksmbd: fix corrupted mtime and ctime in smb2_open

If STATX_BASIC_STATS flags are not given as an argument to vfs_getattr,
It can not get ctime and mtime in kstat.

This causes a problem showing mtime and ctime outdated from cifs.ko.
File: /xfstest.test/foo
Size: 4096            Blocks: 8          IO Block: 1048576 regular file
Device: 0,65    Inode: 2033391     Links: 1
Access: (0755/-rwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Context: system_u:object_r:cifs_t:s0
Access: 2025-07-23 22:15:30.136051900 +0100
Modify: 1970-01-01 01:00:00.000000000 +0100
Change: 1970-01-01 01:00:00.000000000 +0100
Birth: 2025-07-23 22:15:30.136051900 +0100

Cc: stable@vger.kernel.org
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>