[media] drxd_hard: remove unused SIZEOF_ARRAY

SIZEOF_ARRAY is not used (anymore). Besides, ARRAY_SIZE, defined in
include/linux/kernel.h, should be used rather than explicitly coding some
variant of it.

Signed-off-by: Christoph Jaeger <christophjaeger@linux.com>
Reviewed-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>