riscv: Annotate unaligned access init functions

Several functions used in unaligned access probing are only run at
init time. Annotate them appropriately.

Fixes: f413aae9 ("riscv: Set unaligned access speed at compile time")
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20250304120014.143628-11-ajones@ventanamicro.com


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