[media] drx-j: drxj_default_aud_data_g can be static

Fix sparse warning:
	drivers/media/dvb-frontends/drx39xyj/drxj.c:1039:16: sparse: symbol 'drxj_default_aud_data_g' was not declared. Should it be static?

Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>