RISC-V: Stop putting .sbss in .sdata

RISC-V: Stop putting .sbss in .sdata

I don't know why we were doing this, as it's been there since the beginning.
After d841f729e655 ("riscv: force hart_lottery to put in .sdata section") my
guess would be that it made the kernel boot and we forgot to fix it more
cleanly.

The default .bss segment already contains the .sbss section, so we don't need
to do anything additional to ensure the symbols in .sbss continue to work.

Tested-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>