riscv: kprobes: Use patch_text_nosync() for insn slots

These instructions are not yet visible to the rest of the system,
so there is no need to do the whole stop_machine() dance.

Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20240327160520.791322-4-samuel.holland@sifive.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>