V4L/DVB (4106): Fix problems with AV7110 firmware building

Fix missing $() on variable name in dvb/ttpci/Makefile
Fix AV7110 firmware dependencies so that parallel builds work correctly.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>