arm64: defconfig: enable rsu driver

Enable Intel Stratix10 Remote System Update (RSU) driver

The Intel Remote System Update (RSU) driver provides a way for customers
to update the boot configuration of a Intel Stratix 10 SoC device with
significantly reduced risk of corrupting the bitstream storage and
bricking the system.

Signed-off-by: Richard Gong <richard.gong@intel.com>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>