riscv: Introduce PBMT field to PTDUMP

This patch introduces the PBMT field to the PTDUMP, so it can
display the memory attributes for NC or IO.

Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20230921025022.3989723-3-peterlin@andestech.com


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