[media] c8sectpfe: Add LDVB helper functions

These functions are used by the core code for creating the LDVB
devices and adapter.

Addtionally some older SoC's (and potentially newer ones) have different
frontend HW which would allow those devices to be easily supported
in the future by keeping the code specific to the IP separate from the
more generic code.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>