ols: Code cleanup and more debug output.
hwdriver: Add SR_CONF_CLOCK_EDGE option.

Allow the edge of an external clock input to be configured by
means of an SR_CONF_CLOCK_EDGE configuration setting.  This is
a string option with the same format as SR_CONF_TRIGGER_SLOPE.
sysclk-lwla: Implement SR_CONF_CLOCK_EDGE setting.