hw/riscv: Use pre-built bios image of generic platform for virt & sifive_u

Update virt and sifive_u machines to use the opensbi fw_dynamic bios
image built for the generic FDT platform.

Remove the out-of-date no longer used bios images.

Note:

1. To test 32-bit Linux kernel on QEMU 'sifive_u' 32-bit machine,
   the following patch is needed:
   http://lists.infradead.org/pipermail/linux-riscv/2020-July/001213.html

2. To test 64-bit Linux 5.3 kernel on QEMU 'virt' or 'sifive_u' 64-bit
   machines, the following commit should be cherry-picked to 5.3:

   commit 922b0375fc93fb1a20c5617e37c389c26bbccb70
   Author: Albert Ou <aou@eecs.berkeley.edu>
   Date:   Fri Sep 27 16:14:18 2019 -0700

       riscv: Fix memblock reservation for device tree blob

   Linux 5.4 or above already contains this commit/fix.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <1596439832-29238-5-git-send-email-bmeng.cn@gmail.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

Makefile

@@ -254,8 +254,7 @@ u-boot.e500 u-boot-sam460-20100605.bin \
 qemu_vga.ndrv \
 edk2-licenses.txt \
 hppa-firmware.img \
-opensbi-riscv32-sifive_u-fw_jump.bin opensbi-riscv32-virt-fw_jump.bin \
-opensbi-riscv64-sifive_u-fw_jump.bin opensbi-riscv64-virt-fw_jump.bin
+opensbi-riscv32-generic-fw_dynamic.bin opensbi-riscv64-generic-fw_dynamic.bin
 else
 BLOBS=
 endif

hw/riscv/sifive_u.c

@@ -60,9 +60,9 @@
 #include <libfdt.h>
 
 #if defined(TARGET_RISCV32)
-# define BIOS_FILENAME "opensbi-riscv32-sifive_u-fw_jump.bin"
+# define BIOS_FILENAME "opensbi-riscv32-generic-fw_dynamic.bin"
 #else
-# define BIOS_FILENAME "opensbi-riscv64-sifive_u-fw_jump.bin"
+# define BIOS_FILENAME "opensbi-riscv64-generic-fw_dynamic.bin"
 #endif
 
 static const struct MemmapEntry {

hw/riscv/virt.c

@@ -43,9 +43,9 @@
 #include "hw/pci-host/gpex.h"
 
 #if defined(TARGET_RISCV32)
-# define BIOS_FILENAME "opensbi-riscv32-virt-fw_jump.bin"
+# define BIOS_FILENAME "opensbi-riscv32-generic-fw_dynamic.bin"
 #else
-# define BIOS_FILENAME "opensbi-riscv64-virt-fw_jump.bin"
+# define BIOS_FILENAME "opensbi-riscv64-generic-fw_dynamic.bin"
 #endif
 
 static const struct MemmapEntry {