drm/xe: Add outer runtime_pm protection to xe_live_ktest@xe_dma_buf
In the Linux kernel, the following vulnerability has been resolved:

drm/xe: Add outer runtime_pm protection to xe_live_ktest@xe_dma_buf

Any kunit doing any memory access should get their own runtime_pm
outer references since they don't use the standard driver API
entries. In special this dma_buf from the same driver.

Found by pre-merge CI on adding WARN calls for unprotected
inner callers:

<6> [318.639739]     # xe_dma_buf_kunit: running xe_test_dmabuf_import_same_driver
<4> [318.639957] ------------[ cut here ]------------
<4> [318.639967] xe 0000:4d:00.0: Missing outer runtime PM protection
<4> [318.640049] WARNING: CPU: 117 PID: 3832 at drivers/gpu/drm/xe/xe_pm.c:533 xe_pm_runtime_get_noresume+0x48/0x60 [xe]