drm/xe/gt: Fix min() with u32 and u64

Fix the following error while building for 32b:

	In file included from ../drivers/gpu/drm/xe/xe_gt.c:6:
	../drivers/gpu/drm/xe/xe_gt.c: In function ‘gt_ttm_mgr_init’:
	../include/linux/minmax.h:20:35: error: comparison of distinct pointer types lacks a cast [-Werror]
	   20 |         (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
	      |                                   ^~

Cast it to u64 so size of the second operand matches the first one when
building it for 32 bits.
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_gt.c

@@ -183,7 +183,7 @@ static int gt_ttm_mgr_init(struct xe_gt *gt)
 		if (err)
 			return err;
 		gtt_size = min(max((XE_DEFAULT_GTT_SIZE_MB << 20),
-				   gt->mem.vram.size),
+				   (u64)gt->mem.vram.size),
 			       gtt_size);
 		xe->info.mem_region_mask |= BIT(gt->info.vram_id) << 1;
 	}