media: usb: dvb-usb-v2: af9015.c: return 0 instead of 'ret'.

Since 'ret' is known to be 0, just return '0'. This fixes two smatch warnings:

af9015.c:1168 af9015_rc_query() warn: missing error code? 'ret'
af9015.c:1177 af9015_rc_query() warn: missing error code? 'ret'

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>