hw/intc/riscv_aplic: APLICs should add child earlier than realize

hw/intc/riscv_aplic: APLICs should add child earlier than realize

Since only root APLICs can have hw IRQ lines, aplic->parent should
be initialized first.

Fixes: e8f79343cf ("hw/intc: Add RISC-V AIA APLIC device emulation")
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Signed-off-by: yang.zhang <yang.zhang@hexintek.com>
Cc: qemu-stable <qemu-stable@nongnu.org>
Message-ID: <20240409014445.278-1-gaoshanliukou@163.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit c76b121840c6ca79dc6305a5f4bcf17c72217d9c)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>