common/lcd_console: ask only one-time for bg/fg-color per call

Don't call the lcd_getfgcolor and lcd_getbgcolor within the "draw-loop", this
only wastes time.

Signed-off-by: Hannes Petermaier <hannes.petermaier@br-automation.com>
Signed-off-by: Hannes Petermaier <oe5hpm@oevsv.at>
Acked-by: Nikita Kiryanov <nikita@compulab.co.il>