cgroup2: capitalize io stats read and write Op values
cgroup2: capitalize io stats read and write Op values

Signed-off-by: Yashpal Choudhary <eed2ce5074b0b6ac5bf9223cb2c5d8979a67b10a@gmail.com>

opencontainers/runc,kolyshkin/runc,kolyshkin/runc,rhatdan/runc,dqminh/runc,rhatdan/runc,kolyshkin/runc,opencontainers/runc,dqminh/runc,dqminh/runc,rhatdan/runc,dqminh/runc,opencontainers/runc,rhatdan/runc,opencontainers/runc,kolyshkin/runc