arm-trusted-firmware-rockchip: support rk3588

arm-trusted-firmware-rockchip: support rk3588

ATF supports rk3588 since version 2.12, so let's enable it in
arm-trusted-firmware-rockchip.

We still need the TPL to initialize RAM, but keeping rk3588 in rkbin
would cause a duplicate package name, so rename rk3588 to rk3588-tpl in
rkbin.

Finally, point uboot-rockchip for rk3588 to bl31 built by this package,
and add a dependency on the new trusted-firmware-a-rk3588-tpl pacakge.

While this doesn't necessarily add features, we now no longer rely on
the rk3588_bl31_v1.45.elf blob provided by Rockchip, which is always a
good thing.

Tested on Radxa ROCK 5B+.

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>