fs,fsverity: remove check for fsverity being enabled in setattr_prepare()

fs,fsverity: remove check for fsverity being enabled in setattr_prepare()

The check that fs-verity is available in the kernel is not necessary
here. Filesystems could have fsverity files even without fs-verity
enabled. In that case, truncate on fsverity file will succeed, what this
check is trying to prevent.

Fixes: e9734653c523 ("fs,fsverity: reject size changes on fsverity files in setattr_prepare")
Cc: stable@vger.kernel.org
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://patch.msgid.link/20260727094352.1734826-1-aalbersh@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>