HID: lenovo: Add checks to fix of_led_classdev_register

[ Upstream commit 6ae16dfb ]

In lenovo_probe_tpkbd(), the function of_led_classdev_register() could
return an error value that is unchecked. The fix adds these checks.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Change-Id: I089b487588018d38901e95ea3fa0f1d46ff701eb