x86: qemu: Implement PIRQ routing

Support QEMU PIRQ routing via device tree on both i440fx and q35
platforms. With this commit, Linux booting on QEMU from U-Boot
has working ATA/SATA, USB and ethernet.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/qemu-x86_defconfig b/configs/qemu-x86_defconfig
index 0959a98..901cbd7 100644
--- a/configs/qemu-x86_defconfig
+++ b/configs/qemu-x86_defconfig
@@ -2,6 +2,7 @@
 CONFIG_VENDOR_EMULATION=y
 CONFIG_DEFAULT_DEVICE_TREE="qemu-x86_i440fx"
 CONFIG_TARGET_QEMU_X86=y
+CONFIG_GENERATE_PIRQ_TABLE=y
 CONFIG_CMD_NET=y
 CONFIG_OF_CONTROL=y
 CONFIG_VIDEO_VESA=y