am335x, guardian: boot stage feedback in headless mode
This patch enables the guardian board to provide feedback
about the boot stage in headless mode. The on-board led
would behave in the following pattern
* U-boot -> GLOW LED
* Linux -> BLINK LED [HEART-BEAT PATTERN]
Signed-off-by: Moses Christopher <BollavarapuMoses.Christopher@in.bosch.com>