ddr: altera: soc64: Add secure region support for ATF flow

ddr: altera: soc64: Add secure region support for ATF flow

Setting up firewall regions based on SDRAM memory banks configuration
(up to CONFIG_NR_DRAM_BANKS banks) instead of using whole address space.

First 1 MiB (0 to 0xfffff) of SDRAM is configured as secure region,
other address spaces are non-secure regions. The ARM Trusted Firmware (ATF)
image is located in this first 1 MiB memory region. So, this can prevent
software executing at non-secure state EL0-EL2 and non-secure masters
access to secure region.

Add common function for firewall setup and reuse for all SoC64 devices.

Signed-off-by: Alif Zakuan Yuslaimi <alif.zakuan.yuslaimi@altera.com>
Reviewed-by: Tien Fong Chee <tien.fong.chee@altera.com>