gfs2: pass through holder from the VFS for freeze/thaw

[ Upstream commit 62a2175d ]

The filesystem's freeze/thaw functions can be called from contexts where
the holder isn't userspace but the kernel, e.g., during systemd
suspend/hibernate. So pass through the freeze/thaw flags from the VFS
instead of hard-coding them.

Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>