clk: fix build warning for orphan_list

In the backport of commit bdcf1dc25324 ("clk: Evict unregistered clks
from parent caches") to the 4.19.y and 4.14.y stable trees, the
orphan_list structure was placed in the wrong location, causing loads of
build warnings on systems that do not define CONFIG_DEBUG_FS.

Fix this up by moving the structure to the correct place in the file.

Reported-by: "kernelci.org bot" <bot@kernelci.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>