drm/i915: Take object lock in i915_ggtt_pin if ww is not set

i915_vma_wait_for_bind needs the vma lock held, fix the caller.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211216142749.1966107-5-maarten.lankhorst@linux.intel.com