kobject: Remove docstring reference to kset

Currently the docstring for kobject_get_path() mentions 'kset'.  The
kset is not used in the function callchain starting from this function.

Remove docstring reference to kset from the function kobject_get_path().

Signed-off-by: Tobin C. Harding <tobin@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>