media: dvb-frontends: cxd2880: return 0 instead of 'ret'.

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

cxd2880_tnrdmd.c:2165 cxd2880_tnrdmd_check_internal_cpu_status() warn: missing error code? 'ret'
cxd2880_tnrdmd.c:2169 cxd2880_tnrdmd_check_internal_cpu_status() warn: missing error code? 'ret'

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Cc: Yasunari Takiguchi <Yasunari.Takiguchi@sony.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>