drm/tegra: Zero-initialize iosys_map

UBSAN reports an invalid load for bool, as the iosys_map is read
later without being initialized. Zero-initialize it to avoid this.
Reported-by: Ashish Mhetre <amhetre@nvidia.com>
Signed-off-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230901115910.701518-2-cyndis@kapsi.fi

drivers/gpu/drm/tegra/gem.c

@@ -177,7 +177,7 @@ static void tegra_bo_unpin(struct host1x_bo_mapping *map)
 static void *tegra_bo_mmap(struct host1x_bo *bo)
 {
 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
-	struct iosys_map map;
+	struct iosys_map map = { 0 };
 	int ret;
 
 	if (obj->vaddr)