target/riscv: Remove additional priv version check for mcountinhibit

target/riscv: Remove additional priv version check for mcountinhibit

With .min_priv_version, additiona priv version check is uncessary
for mcountinhibit read/write functions.

Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Message-Id: <20220816232321.558250-7-atishp@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>