drm/xe: Don't rely on xe_assert.h to be included elsewhere

While xe_assert.h is now included and used by the xe_force_wake.h,
we want to stop include xe_force_wake.h from xe_device.h as it's
not needed there.  Explicitly include xe_assert.h where needed.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240507110959.2747-2-michal.wajdeczko@intel.com