drm/xe/tests/pci: Check dma_mask_size, va_bits and vm_max_level

drm/xe/tests/pci: Check dma_mask_size, va_bits and vm_max_level

Members dma_mask_size, va_bits and vm_max_level of struct xe_device_desc
are all expected to be non-zero.  Add checks for that in
check_platform_desc().

Suggested-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20251020-xe-kunit-dma_mask_size-va_bits-vm_max_level-v2-2-27b03971bc7e@intel.com
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>