ARM: 9323/1: mm: Fix ARCH_LOW_ADDRESS_LIMIT when CONFIG_ZONE_DMA

Configuring VMSPLIT_2G + LPAE on Raspberry Pi 4 leads to SWIOTLB
buffer allocation beyond platform dma_zone_size of SZ_1G, which
results in broken SD card boot.

So fix this be setting ARCH_LOW_ADDRESS_LIMIT in CONFIG_ZONE_DMA
case.

Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Fixes: e9faf9b0 ("ARM: add multi_v7_lpae_defconfig")
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>