common: board_r: rework BOOT LED handling

common: board_r: rework BOOT LED handling

Rework BOOT LED handling. There is currently one legacy implementation
for BOOT LED from Status Led API.

This work on ancient implementation used by BOOTP by setting the LED
to Blink on boot and to turn it OFF when the firmware was correctly
received by network.

Now that we new LED implementation have support for LED boot, rework
this by also set the new BOOT LED to blink and also set it to ON before
entering main loop to confirm successful boot.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>