base/platform: Simplifications for NULL platform data/resources handling

There's no need to explicitly check for data and resources being NULL,
as platform_device_add_{data,resources}() do this internally nowadays.

This makes the code more linear and less indented.

Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>