riscv: Enforce DWARF4 output

Since commit 409e4b547872 ("Makefile: Enforce DWARF4 output") the
whole U-Boot build switched to enforce DWARF4 output, but RISC-V
is still on its own setting. Let's switch to use U-Boot's setting.

Signed-off-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>
1 file changed