thermal: qoriq: Fix error path of calling qoriq_tmu_register_tmu_zone fail

When registering tmu zone failed, the error path should be err_tmu
instead of err_iomap, as iounmap() needs to be called.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>