classes: add aarch64_be target

Add big endian ARMv8 target to OE infrastructure

Signed-off-by: Victor Kamensky <victor.kamensky@linaro.org>
Signed-off-by: Koen Kooi <koen.kooi@linaro.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
kernel-yocto: Add a missing '['

Signed-off-by: Peter Kjellerstedt <peter.kjellerstedt@axis.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>