fs: dlm: Simplify buffer size computation in dlm_create_debug_file()

stable inclusion
from stable-v6.6.2
commit 4bc46c047ecf1818e6a053fbb399aab9c476c16d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8IW7G

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4bc46c047ecf1818e6a053fbb399aab9c476c16d



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[ Upstream commit 19b3102c0b5350621e7492281f2be0f071fb7e31 ]

Use sizeof(name) instead of the equivalent, but hard coded,
DLM_LOCKSPACE_LEN + 8.

This is less verbose and more future proof.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>