V4L/DVB (10565): bttv: fix external mux for RemoteVision MX

V4L/DVB (10565): bttv: fix external mux for RemoteVision MX

Old versions of the bttv driver would use the high nibble of an input's
muxsel value to program the GPIO lines enabled via gpiomask2.  Apparently
this was supposed to be for switching external audio muxes.  Anyway, the
code that did this was removed sometime in the pre-git 2.6 series.

The RemoteVision MX board used this feature to control an external video
mux and I guess no one noticed when they removed the code.

Move the extra gpio mux data out of the high nibble of muxsel and to
rv605_muxsel(), then have that function set the gpio lines with it.

From looking at the CD22M3494E datasheet, it seems like the mdelay(1) is a
much longer delay than necessary.  It looks like only around 20 ns is
necessary.

Cc: Miguel Freitas <miguel@cetuc.puc-rio.br>
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>