Add build stage for Rock PI 4

Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
2 jobs for master in 2 minutes and 23 seconds (queued for 5 seconds)
Status Job ID Name Coverage
  Build
passed #17758
imx8mq-evk

00:02:23

failed #17759
rock-pi-4

00:01:59

 
Name Stage Failure
failed
rock-pi-4 Build
  MKIMAGE tpl/u-boot-tpl-rockchip.bin
CAT idbloader.img
CAT u-boot-rockchip.bin
CFGCHK u-boot.cfg
$ git clone --depth 1 https://github.com/rockchip-linux/rkbin.git
Cloning into 'rkbin'...
$ (cd rkbin && mkimage -n rk3399 -T rksd -d bin/rk33/rk3399_ddr_800MHz_*.bin idbloader.img && cat bin/rk33/rk3399_miniloader_v*.bin >> idbloader.img
/bin/bash: eval: line 109: syntax error: unexpected end of file
ERROR: Job failed: exit code 2