fsa9480: Remove obsolete cleanup for clientdata
A few new i2c-drivers came into the kernel which clear the clientdata-pointer
on exit or error. This is obsolete meanwhile, the core will do it.

modified:   drivers/misc/fsa9480.c
ref: a3b49472e5718aac53d5d1ce045b82e29f9df340
Signed-off-by: cholokei <leesl0416@naver.com>