video: fbdev: udlfb: replace snprintf in show functions with sysfs_emit

stable inclusion
from stable-v5.10.110
commit 681a317034b214c30177162235690a401158cf43
bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=681a317034b214c30177162235690a401158cf43



--------------------------------

[ Upstream commit 81a99828 ]

Use sysfs_emit instead of scnprintf, snprintf or sprintf.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Jing Yao <yao.jing2@zte.com.cn>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yu Liao <liaoyu15@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>