drm/i915: Populate logical context during first pin.

This allows us to remove pin_map from state allocation, which saves
us a few retry loops. We won't need this until first pin, anyway.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
[danvet: Resolve context conflict because we don't have the
i915_scheduler.c extraction from the below patches set:
https://lore.kernel.org/intel-gfx/20210203165259.13087-6-chris@chris-wilson.co.uk/

]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-19-maarten.lankhorst@linux.intel.com