riscv: Change check_unaligned_access_speed_all_cpus to void

The return value of check_unaligned_access_speed_all_cpus() is always
zero, so make the function void so we don't need to concern ourselves
with it. The change also allows us to tidy up
check_unaligned_access_all_cpus() a bit.

Reviewed-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250304120014.143628-14-ajones@ventanamicro.com


Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>