board: qemu-arm: select CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR

board: qemu-arm: select CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR

qemu_arm64_defconfig with CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=n leads to a
build error:

    arch/arm/lib/crt0_64.S:85:
    Error: constant expression expected at operand 2 --
    `ldr x0,=((CFG_SYS_INIT_RAM_ADDR+CFG_SYS_INIT_RAM_SIZE-480))'

We do not define CFG_SYS_INIT_RAM_ADDR and CFG_SYS_INIT_RAM_SIZE for QEMU.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>