Add support for FunctionFS-based function
Both mtp-responder and sdbd have FunctionFS backend now what
allows to use them in ConfigFS implementation of HAL.
We use systemd socke activation with special socket type
which starts the service when needed. There is an assumption
that each of those services provides a suitable .socket file.
Change-Id: Ib073ac10f6d12bb75f20e4b9f3961bcdbd21520c
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>