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().

Fixes: 12422af8

 ("pinctrl: Add Intel Thunder Bay pinctrl driver")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Reviewed-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20221129120126.1567338-1-cuigaosheng1@huawei.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>