configs: qemu-arm raise CONFIG_NR_DRAM_BANKS

configs: qemu-arm raise CONFIG_NR_DRAM_BANKS

The number of memory banks in QEMU is not bounded by 1.

In this example we have two banks:

    qemu-system-aarch64 \
    -machine virt \
    -nographic \
    -cpu cortex-a72 \
    -m 8G \
    -smp 8,sockets=2,cores=4,threads=1 \
    -object memory-backend-ram,id=mem0,size=4G \
    -numa node,cpus=0-3,memdev=mem0 \
    -object memory-backend-ram,id=mem1,size=4G \
    -numa node,cpus=4-7,memdev=mem1 \
    -bios u-boot.bin

Use the default value defined in /Kconfig as 4.

Suggested-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Suggested-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>