target: riscv: Enable Bit Manip for OpenTitan Ibex CPU

target: riscv: Enable Bit Manip for OpenTitan Ibex CPU

The OpenTitan Ibex CPU now supports the the Zba, Zbb, Zbc
and Zbs bit-manipulation sub-extensions ratified in
v.1.0.0 of the RISC-V Bit- Manipulation ISA Extension, so let's enable
them in QEMU as well.

1: https://github.com/lowRISC/opentitan/pull/9748

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20240823003231.3522113-1-alistair.francis@wdc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>