smb/client: fix buffer size for smb311_posix_qinfo in smb2_compound_op()

[ Upstream commit 12c43a062acb0ac137fc2a4a106d4d084b8c5416 ]

Use `sizeof(struct smb311_posix_qinfo)` instead of sizeof its pointer,
so the allocated buffer matches the actual struct size.

Fixes: 6a5f6592a0b6 ("SMB311: Add support for query info using posix extensions (level 100)")
Reported-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: ZhangGuoDong <zhangguodong@kylinos.cn>
Reviewed-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>