target/riscv: Fixup MSECCFG minimum priv check

target/riscv: Fixup MSECCFG minimum priv check

There is nothing in the RISC-V spec that mandates version 1.12 is
required for ePMP and there is currently hardware [1] that implements
ePMP (a draft version though) with the 1.11 priv spec.

1: https://ibex-core.readthedocs.io/en/latest/01_overview/compliance.html

Fixes: a4b2fa433125 ("target/riscv: Introduce privilege version field in the CSR ops.")
Signed-off-by: Alistair Francis <[email protected]>
Reviewed-by: Bin Meng <[email protected]>
Message-Id: <20220629233102[email protected]>