arm64: marvell: Enable SEI driver

Enable the newly introduced Marvell SEI driver for the 64-bit Marvell
EBU platforms.

Suggested-by: Haim Boot <hayim@marvell.com>
Reviewed-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>