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 <[e-mail]>
Signed-off-by: Mikko Perttunen <[e-mail]>
Signed-off-by: Thierry Reding <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/tegra/gem.c

···
 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)