arm64: defconfig: enable the Safexcel crypto engine as a module

The Safexcel EIP197 cryptographic engine is used on some Marvell SoCs,
such as Armada 7040 and Armada 8040. Enable this driver as a module in
the ARM64 defconfig.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>