Update BIOS_FILENAME to consider 32-bit bios image file name.

Tested booting Linux v5.5 32-bit image (built from rv32_defconfig
plus CONFIG_SOC_SIFIVE) with the default 32-bit bios image.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
---

Changes in v2: None

 hw/riscv/sifive_u.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
index ca561d3..371133e 100644
--- a/hw/riscv/sifive_u.c
+++ b/hw/riscv/sifive_u.c
@@ -57,7 +57,11 @@
 
 #include <libfdt.h>
 
-#define BIOS_FILENAME "opensbi-riscv64-sifive_u-fw_jump.bin"
+#if defined(TARGET_RISCV32)
+# define BIOS_FILENAME "opensbi-riscv32-sifive_u-fw_jump.bin"
+#else
+# define BIOS_FILENAME "opensbi-riscv64-sifive_u-fw_jump.bin"
+#endif
 
 static const struct MemmapEntry {
     hwaddr base;
-- 
2.7.4