greybus: endo: delete "0xXXXX" portion in sysfs "endo" directory

With the Endo "id" attribute in place, there's no need to encode
the ID of an Endo in its sysfs path.  So get rid of it.

Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>