LEDS: memory leak in blinkm_led_common_set()

This can return without freeing the bl_work struct.  Also there was no
check for allocation failure.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Jan-Simon Möller <jansimon.moeller@gmx.de>
Signed-off-by: Bryan Wu <bryan.wu@canonical.com>