target/riscv: Fix th.dcache.cval1 priviledge check

target/riscv: Fix th.dcache.cval1 priviledge check

According to the specification, the th.dcache.cvall1 can be executed
under all priviledges.
The specification about xtheadcmo located in,
https://github.com/T-head-Semi/thead-extension-spec/blob/master/xtheadcmo/dcache_cval1.adoc

Signed-off-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Christoph Muellner <christoph.muellner@vrull.eu>
Message-ID: <20231208094315.177-1-zhiwei_liu@linux.alibaba.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>