fastrpc: sdsprpcd: Implement sdsprpcd

The boilerplate for adsprpcd and cdsprpcd can be reused with one
exception: a different ioctl call (FASTRPC_IOCTL_INIT_ATTACH_SNS) is
used to attach to the sensor domain.

Signed-off-by: Ola Jeppsson <ola@snap.com>
Acked-by: Heinrich Fink <hfink@snap.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>