RISC-V: better error message when reporting unsupported satp modes

ADDITIONAL SYSTEM INFORMATION :
Debian Riscv64 in Qemu 7.2

A DESCRIPTION OF THE PROBLEM :
In said system the satp mode is sv57.
The error message on startup is: "Unsupported satp mode: sv57" then the VM finishes.
I had to dig in the sources to find out what this message means.
In file "./src/hotspot/cpu/riscv/vm_version_riscv.cpp" I found this:
  // check if satp.mode is supported, currently supports up to SV48(RV64)
  if (get_satp_mode() > VM_SV48) {
    vm_exit_during_initialization(err_msg("Unsupported satp mode: %s", _vm_mode));
  }
. Please add the information that only satp modes up to sv48 are supported.