Merge patch series "riscv: Increase mmap_rnd_bits_max on Sv48/57"

Sami Tolvanen <samitolvanen@google.com> says:

We noticed that 64-bit RISC-V kernels limit mmap_rnd_bits to 24
even if the hardware supports a larger virtual address space size
[1]. These two patches allow mmap_rnd_bits_max to be changed during
init, and bumps up the maximum randomness if we end up setting up
4/5-level paging at boot.

* b4-shazam-merge:
  riscv: mm: Update mmap_rnd_bits_max
  mm: Change mmap_rnd_bits_max to __ro_after_init

Link: https://lore.kernel.org/r/20230929211155.3910949-4-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>