Input: sparkspkr - move remove() functions to .devexit.text

The function bbc_remove and grover_remove are used only wrapped
by __devexit_p so define it using __devexit.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>