target/mips: Only update MVPControl.EVP bit if executed by master VPE

target/mips: Only update MVPControl.EVP bit if executed by master VPE

According to the 'MIPS MT Application-Specific Extension' manual:

  If the VPE executing the instruction is not a Master VPE,
  with the MVP bit of the VPEConf0 register set, the EVP bit
  is unchanged by the instruction.

Modify the DVPE/EVPE opcodes to only update the MVPControl.EVP bit
if executed on a master VPE.

Cc: qemu-stable@nongnu.org
Reported-by: Hansni Bu
Buglink: https://bugs.launchpad.net/qemu/+bug/1926277
Fixes: f249412c749 ("mips: Add MT halting and waking of VPEs")
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-ID: <20210427133343.159718-1-f4bug@amsat.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>