input: ft5x06: check return value of kobject_create_and_add

The Focaltech driver creates a sysfs under sys/kernel/ts_info
to access touch panel details. However, the return value of the
API is not checked properly. Check the return value of the API.
Also avoid making a duplicate copy of the kobject and clean up
the show routine.

Change-Id: Ib36e9d7661ee3d2ce7b229d8692e6212e33cbf36
Signed-off-by: Himanshu Aggarwal <haggarwa@codeaurora.org>