drm/xe: Remove mem_access from suspend and resume functions

At these points, we are sure that device is awake in D0.
Likely in the middle of the transition, but awake. So,
these extra protections are useless. Let's remove it and
continue with the killing of xe_device_mem_access.

Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240222163937.138342-12-rodrigo.vivi@intel.com