[clang][RISCV] Change default abi with f extension but without d extension (#73489)

Now we have default abi lp64 for rv64if and ilp32 for rv32if, which is
different with riscv-gnu-toolchain. In
https://github.com/riscv-collab/riscv-gnu-toolchain/blob/8e9fb09a0c4b1e566492ee6f42e8c1fa5ef7e0c2/configure#L3385
when have f and not d, it prefers lp64f/ilp32f but no soft float. This
patch tries to make their behaviors consistent.