V4L/DVB (10531): Code rearrangements in preparation for other report types

LED_REPORT and all flash REPORTs are on it's way. This code rearrangement
cleans up the code for proper integration later on.

Signed-off-by: Tobias Lorenz <tobias.lorenz@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>