riscv: Add new csr defines related to vector extension

Follow the riscv vector spec to add new csr numbers.

[guoren@linux.alibaba.com: first porting for new vector related csr]
Acked-by: Guo Ren <guoren@kernel.org>
Co-developed-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Co-developed-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>