riscv: add RISC-V fields to bdinfo command

The firmware invoking main U-Boot uses

* a0 to pass the boot hart
* a1 to pass a device-tree

Let the bdinfo command print this information, e.g.

    boot hart   = 0x000000000000001b
    firmware fdt= 0x0000000087e00000

The firmware fdt field will only be printed if it is non-zero.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
index 9a05b66..65dc49f 100644
--- a/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@ -26,6 +26,7 @@
 obj-$(CONFIG_$(SPL_)SMP) += smp.o
 obj-$(CONFIG_SPL_BUILD)	+= spl.o
 obj-y   += fdt_fixup.o
+obj-$(CONFIG_$(SPL)CMD_BDI) += bdinfo.o
 
 # For building EFI apps
 CFLAGS_NON_EFI := -fstack-protector-strong