uboot-imx

rockchip: enable boot0-hook for all Rockchip SoCs

Rockchip SoCs bootrom design is like this:
- First 2KB or 4KB internal memory is for bootrom stack and heap;
- Then the first 4-byte suppose to be a TAG like 'RK33';
- The the following memory address end with '0004' is the first
  instruction load and running by bootrom;

Let's use the boot0 hook to reserve the first 4-byte tag for all
the Rockchip SoCs.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
[Commit message taken from an older patch by:]
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>