All supported Rockchip SoCs (RK3288, RK3328, RK3368 and RK3399)
have non-continuous memory areas in the linker script with a huge
gap between them. This results in extremely padded binary images
with a size of about 4 GiB.

E.g. on the RK3399 we have the following memory areas (and base addresses):
RAM (0x1000), SRAM (0xFF8C0000), and PMUSRAM (0xFF3B0000).

Consumers of the TF-A project (e.g. coreboot or U-Boot) therefore
use the ELF image instead, which has a size of a few hundred kBs.

In order to prevent the generation of a huge and useless file,
this patch disables the binary generation for all affected Rockchip
SoCs.

Signed-off-by: Christoph Müllner <christophm30@gmail.com>
Change-Id: I4ac65bdf1e598c3e1a59507897d183aee9a36916