[DG2][small-bar] Crash when setting XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM to lmem only BOs

While fixing a clear-color issue in small-bar system in Mesa I caught this crash:dmesg.txt

[ 490.912495] xe_exec_ioctl+0xba9/0xce0 [xe] is line 363 from xe_exec.c(xe_vm_fence_all_extobjs(vm, &job->drm.s_fence->finished)

Steps to reproduce:

• Disable resizable bar
• Build and install Xe KMD with head: aeac46cf "Revert "FIXME: drm/i915: add a lot of includes in intel_display_power.h""
• Build and install Mesa from https://gitlab.freedesktop.org/zehortigoza/mesa/-/commits/iris-clear-color-fix-debug
• start Gnome with Wayland protocol(necessary to enable clear-color)
• start Firefox(also reproduced when starting Steam, probably any applications that make a bit of GPU usage will reproduce it)

Note: These clear-color BOs are lmem only + XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM + external/exported.