i.MX8MP's market segment fuse field is bit[6:5], correct it.

Fixes: 83fe39ad ("cpufreq: imx-cpufreq-dt: Add i.MX8MP support")
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>