arm64: mvebu: defconfig: enable CONFIG_AHCI_MVEBU

This patch enables the new ahci mvebu driver for marvell arm64 platform
SOCs(A3k and A8k). And since AHCI_MVEBU selects SCSI_AHCI, so
"CONFIG_SCSI_AHCI=y" is removed from those default config files.

Signed-off-by: Ken Ma <make@marvell.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Stefan Roese <sr@denx.de>