spcom: silent error messages until spss link is up

After spss reset (a.k.a SSR) the spdaemon tries to open spcom char dev.
Avoid flooding the kernel log with error messages until the spss link
is up.

Change-Id: I7abd37f50fa4c172e07c8551c287b6ccf0511a44
Signed-off-by: Amir Samuelov <amirs@codeaurora.org>