arm64: defconfig: enable Layerscape SFP driver

Enable the driver for the Layerscape SFP (Security Fuse Processor) found
on most Layerscape SoCs. For example, a per-device unique serial number
is stored in the fuses.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>