drm/i915/selftests: handle object rounding

Ensure we account for any object rounding due to min_page_size
restrictions.

Signed-off-by: Matthew Auld <[e-mail]>
Cc: Thomas Hellström <[e-mail]>
Cc: Ramalingam C <[e-mail]>
Reviewed-by: Ramalingam C <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/i915/gt/selftest_migrate.c

···
 	if (IS_ERR(src))
 		return 0;
 
+	sz = src->base.size;
 	dst = i915_gem_object_create_internal(i915, sz);
 	if (IS_ERR(dst))
 		goto err_free_src;