drm/xe: Add xe_device_asid_to_vm helper

drm/xe: Add xe_device_asid_to_vm helper

Introduce the xe_device_asid_to_vm helper, which can be used throughout
the driver to resolve the VM from a given ASID.

v4:
 - Move forward declare after includes (Stuart)

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matt Atwood <matthew.s.atwood@intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
Tested-by: Stuart Summers <stuart.summers@intel.com>
Link: https://patch.msgid.link/20260116221731.868657-5-matthew.brost@intel.com