pinctrl: thunderbay: fix possible memory leak in thunderbay_build_functions()

In the Linux kernel, the following vulnerability has been resolved: pinctrl: thunderbay: fix possible memory leak in thunderbay_build_functions() The thunderbay_add_functions() will free memory of thunderbay_funcs when everything is ok, but thunderbay_funcs will not be freed when thunderbay_add_functions() fails, then there will be a memory leak, so we need to add kfree() when thunderbay_add_functions() fails to fix it. In addition, doing some cleaner works, moving kfree(funcs) from thunderbay_add_functions() to thunderbay_build_functions().