The next commit wants to be able to call fini() from an init() failure
path to remove the need to duplicate a bunch of cleanup.

Moving fini() above init() avoids the need for a forward-declaration.
Signed-off-by: Ben Skeggs <bskeggs@nvidia.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240726043828.58966-2-bskeggs@nvidia.com