gpio: max7301: add missing __devexit marking

The remove member of the spi_driver max7301_driver uses __devexit_p(), so
the remove function itself should be marked with __devexit.  Even more so
considering the probe function is marked with __devinit.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Acked-by: Juergen Beisert <j.beisert@pengutronix.de>
Cc: Dmitry Baryshkov <dbaryshkov@gmail.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>