target/riscv: additional macros to check instruction support

target/riscv: additional macros to check instruction support

Given that the 128-bit version of the riscv spec adds new instructions, and
that some instructions that were previously only available in 64-bit mode
are now available for both 64-bit and 128-bit, we added new macros to check
for the processor mode during translation.
Although RV128 is a superset of RV64, we keep for now the RV64 only tests
for extensions other than RVI and RVM.

Signed-off-by: Frédéric Pétrot <frederic.petrot@univ-grenoble-alpes.fr>
Co-authored-by: Fabien Portas <fabien.portas@grenoble-inp.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20220106210108.138226-5-frederic.petrot@univ-grenoble-alpes.fr
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>