Input: tegra-kbc - correct call to input_free_device

If kzalloc for kbc fails, then we have NULL pointer dereference while
calling input_free_device(kbc->idev) in the error handling.
So it is safer to always use the original name, input_dev.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/keyboard/tegra-kbc.c

@@ -702,7 +702,7 @@ err_iounmap:
 err_free_mem_region:
 	release_mem_region(res->start, resource_size(res));
 err_free_mem:
-	input_free_device(kbc->idev);
+	input_free_device(input_dev);
 	kfree(kbc);
 
 	return err;