mvebu: x530: Reduce SPL image size

Currently, building U-Boot for x530 fails since the SPL image is too
big. This patch reduces the SPL size by changing the following Kconfig
options:

Enable CONFIG_SPL_TINY_MEMSET
Disable CONFIG_SPI_FLASH_BAR

By disabling CONFIG_SPI_FLASH_BAR, the tiny SPI NOR framework can be
used.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Chris Packham <chris.packham@alliedtelesis.co.nz>
Cc: Pratyush Yadav <p.yadav@ti.com>
Cc: Tom Rini <trini@konsulko.com>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Acked-by: Pratyush Yadav <p.yadav@ti.com>