led: led_cortina: Add CAxxx LED support

Add Cortina Access LED controller support for CAxxxx SOCs

Signed-off-by: Jway Lin <jway.lin@cortina-access.com>
Signed-off-by: Alex Nemirovsky <alex.nemirovsky@cortina-access.com>
CC: Simon Glass <sjg@chromium.org>

Add head file fixed link error and remove unused flashing function
Reviewed-by: Simon Glass <sjg@chromium.org>