media: ddbridge: remove unneeded *fe vars from attach functions

These are only used in C/T demod attach functions, don't add any real
benefit (ie. line length savings) and in case of cxd28xx_attach aren't
even used consequently. Remove them.

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>