riscv: mm: update T-Head memory type definitions

Update T-Head memory type definitions according to C910 doc [1]
For NC and IO, SH property isn't configurable, hardcoded as SH,
so set SH for NOCACHE and IO.

And also set bit[61](Bufferable) for NOCACHE according to the
table 6.1 in the doc [1].

Link: https://github.com/T-head-Semi/openc910 [1]
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reviewed-by: Guo Ren <guoren@kernel.org>
Tested-by: Drew Fustini <dfustini@baylibre.com>
Link: https://lore.kernel.org/r/20230912072510.2510-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>