riscv: mm: Add page fault trace points

Add page fault trace points, which are useful to implement RV monitor that
watches page faults.

Signed-off-by: Nam Cao <namcao@linutronix.de>
Acked-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>