This commit supplements commit 7d877fbb. External sync mode is now
disabled if XBAR connection fails and config options are used directly
in sync_src variable and passed to XBAR macro only when needed. The first
option could caused an undefined behaviour when sync_src was equal to -1
(external sync not used)
Signed-off-by: Michal Lenc <michallenc@seznam.cz>
11cf3de776