soc: qcom: spcom: create control channel

For commands that don't required SPU communication: is-link-up and
create channel, instead of using sp_kernel channel (the one used for
application loading) control channel /dev/spcom used.

Change-Id: I4d6abd83d77f3b1a3d277dbfec076faa0cbc72af
Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>