drm/xe: Refactor dma_mask_size

dma_mask_size is more related to the platform than the GT IP. Thus
move it to platform descriptors.

v2:
 - Rebase

Signed-off-by: Sai Teja Pottumuttu <sai.teja.pottumuttu@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250130085804.4136497-2-sai.teja.pottumuttu@intel.com


Signed-off-by: Matt Roper <matthew.d.roper@intel.com>