rockchip: boot0 hook: support early return for RK3188/RK3066-style BROM

rockchip: boot0 hook: support early return for RK3188/RK3066-style BROM

Some Rockchip BROM versions (e.g. the RK3188 and RK3066) first read 1KB data
from NAND into SRAM and executes it. Then, following a return to bootrom, the
BROM loads additional code to SRAM (not overwriting the first block read) and
reenters at the same address as the first time.

To support booting either a TPL (on the RK3066) or SPL (on the RK3188) using
this model of having to count entries, this commit adds code to the boot0
hook to track the number of entries and handle them accordingly.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Signed-off-by: Paweł Jarosz <paweljarosz3691@gmail.com>
Tested-by: Andy Yan <andy.yan@rock-chips.com>