automation: make console options configurable via variables

automation: make console options configurable via variables

This makes the test script easier reusable for different runners, where
console may be connected differently. Include both console= option and
configuration for specific chosen console too (like com1= here) in the
'CONSOLE_OPTS' variable.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>