Input: tps6507x-ts - remove unneeded NULL test

Stanse found that tsc is dereferenced earlier than checked for being
NULL in tps6507x_ts_remove. Remove the test because there is no way
for tsc to be NULL there.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>