media: lgdt3306a: fix lgdt3306a_search()'s return type

The method dvb_frontend_ops::search() is defined as
returning an 'enum dvbfe_search', but the implementation in this
driver returns an 'int'.

Fix this by returning 'enum dvbfe_search' in this driver too.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Acked-by: Brad Love <brad@nextdimension.cc>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>