The legacy chips like rk3188 maskrom require all IDB data with RC4,
the boot_merger pack the loader with a rc4 flag in header,
and the upgrade_tool will write the data with rc4 to IDB area.
usage:
boot_merger --rc4 RKBOOT/RK310BMINIALL.ini
and you can see log below if success with RC4:
* enable RC4 for IDB data(both ddr and preloader)
Test on rk3188.
Change-Id: If221a32a462bb43bef67aae802adff5e1e8436ac
Signed-off-by: Joseph Chen <chenjh@rock-chips.com>