V4L/DVB (8006): em28xx: Split HVR900 into two separate entries

 - Separate the newer variant of the HVR-900 into its own device profile
   because it has a Micronas DRX397 instead of the Zarlink demod.  This
   doesn't make the device work, but at least we don't try to initialize it
   as though it had the Zarlink device.

Signed-off-by: Devin Heitmueller <devin.heitmueller@gmail.com>
[mchehab@infradead.org: avoid compilation breakage at mainstream, where drx397xD.h doesn't exist yet]
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>