at91bootstrap: add 3.8.13 recipe
at91bootstrap: add 3.8.13 recipe

Use the v3.8.13-rc2 tag.

Signed-off-by: Razvan Stefanescu <f4ee3fcb6e54dcf71fbaefdd500eea5cee1f4f99@microchip.com>

linux4sam/meta-atmel,linux4sam/meta-atmel,linux4sam/meta-atmel,alexandrebelloni/meta-atmel,linux4sam/meta-atmel,alexandrebelloni/meta-atmel,alexandrebelloni/meta-atmel,linux4sam/meta-atmel