thermal: qoriq: Use devm_platform_ioremap_resource() instead of of_iomap()

Use devm_platform_ioremap_resource() instead of of_iomap() to
save the iounmap() call in error handle path;

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>