media: lgdt330x.h: fix compiler warning

media: lgdt330x.h: fix compiler warning

Add missing 'inline' to fix this compiler warning:

In file included from drivers/media/common/b2c2/flexcop-fe-tuner.c:21:0:
drivers/media/dvb-frontends/lgdt330x.h:61:22: warning: 'lgdt330x_attach' defined but not used [-Wunused-function]
 struct dvb_frontend *lgdt330x_attach(const struct lgdt330x_config *config,
                      ^~~~~~~~~~~~~~~

Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Suggested-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>