panfrost: Don't call panfrost_vt_init for compute

Given we emit shared memory immediately after anyway, the function call
doesn't do anything but zero-initializing the payload and setting some
magic bits. We can do that ourselves at the call site.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6476>
3 files changed