input: sensors: fix incorrect use of input_free_device()

Input_free_device() should only be used if input_register_device()
was not called yet or if it failed, some sensor drivers does not
use this correctly, this may cause null pointer exception when
unbinding driver or binding fails.

Change-Id: I04d455dd9cd59ab76be7d621815ad70668c0bac1
Signed-off-by: Bingzhe Cai <bingzhec@codeaurora.org>