V4L/DVB (13583): DiB8090: Add the DiB0090 tuner driver and STK8096GP-board

This patchs adds support for the DiBcom DiB0090 RF tuner and for
DiBcom's reference design STK8096GP. Small extracts of the DiB0070 and
the DiB8000-driver into a common codebase.

Signed-off-by: Patrick Boettcher <pboettcher@kernellabs.com>
Signed-off-by: Olivier Grenie <Olivier.Grenie@dibcom.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>