drm/i915/guc: Properly initialise kernel contexts

drm/i915/guc: Properly initialise kernel contexts

If a context has already been registered prior to first submission
then context init code was not being called. The noticeable effect of
that was the scheduling priority was left at zero (meaning super high
priority) instead of being set to normal. This would occur with
kernel contexts at start of day as they are manually pinned up front
rather than on first submission. So add a call to initialise those
when they are pinned.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221102192109.2492625-2-John.C.Harrison@Intel.com