The HDCP blob is only for the RK3399, so it is not needed on RK3588.
The blob being present during build pollutes the license with
"UnfreeRedistributable" unnecessary as it is not contained in the
output.
The SHA256 hash bl31.elf with HDCP.bin available and unavailable in the
build tree are identical.
cf1c4e4e8c6803a1e8185af8b45318729167cee0336c105f19037edfb9b2d956 removed/bl31.elf
cf1c4e4e8c6803a1e8185af8b45318729167cee0336c105f19037edfb9b2d956 available/bl31.elf
42903be7da