target/riscv: Pass the same value to oprsz and maxsz.

target/riscv: Pass the same value to oprsz and maxsz.

Since commit e2e7168a214b0ed98dc357bba96816486a289762, if oprsz
is still zero(as we don't use this field), simd_desc will trigger an
assert.

Besides, tcg_gen_gvec_*_ptr calls simd_desc in it's implementation.
Here we pass the value to maxsz and oprsz to bypass the assert.

Signed-off-by: LIU Zhiwei <zhiwei_liu@c-sky.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210521054816.1784297-1-zhiwei_liu@c-sky.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>