riscv: Fix text patching when IPI are used

riscv: Fix text patching when IPI are used

For now, we use stop_machine() to patch the text and when we use IPIs for
remote icache flushes (which is emitted in patch_text_nosync()), the system
hangs.

So instead, make sure every CPU executes the stop_machine() patching
function and emit a local icache flush there.

Co-developed-by: Björn Töpel <bjorn@rivosinc.com>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20240229121056.203419-3-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>