drm/v3d: centralize error handling when init scheduler fails

Remove redundant error message (since now it is very similar to what
we do in drm_sched_init) and centralize all error handling in a
unique place, as we follow the same steps in any case of failure.

Signed-off-by: Melissa Wen <mwen@igalia.com>
Acked-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220228181647.3794298-1-mwen@igalia.com