riscv: s64ilp32: Add asid support

The s32ilp32 uses 9 bits as asid_bits because of the xlen=32
limitation of CSR. The xlen of s64ilp32 is 64 bits in width, and
the SATP CSR format is the same for Sv32, Sv39, Sv48, and Sv57. So
this patch makes asid mechanism support s64ilp32 with maximum
num_asids.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>