media: ddbridge: fix build warnings

Fix 2 build warnings.
These functions are void, so drop the "return"s.

./drivers/media/pci/ddbridge/ddbridge-io.h: warning: 'return' with a value, in function returning void [enabled by default]:  => 50:2, 55:2

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Daniel Scheller <d.scheller.oss@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>