V4L/DVB (5130): M920x: misc updates and fixes

- hardware pid filtering no longer enabled unless in usb 1.x mode
- more responsive rc handling
- some minor bug fixes and code refolding
- m9206_write delay dropped (doesn't seem to be needed)

Signed-off-by: Aapo Tahkola <aet@rasterburn.org>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>