target/riscv: Add zicfilp extension

target/riscv: Add zicfilp extension

zicfilp [1] riscv cpu extension enables forward control flow integrity.
If enabled, all indirect calls must land on a landing pad instruction.

This patch sets up space for zicfilp extension in cpuconfig. zicfilp
is dependend on zicsr.

[1] - https://github.com/riscv/riscv-cfi

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Co-developed-by: Jim Shu <jim.shu@sifive.com>
Co-developed-by: Andy Chiu <andy.chiu@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20241008225010.1861630-3-debug@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>