intel: fcs: disable to request random number generation on Stratix10 platform

According to the README.md of ATF code, whose repo is
https://github.com/altera-opensource/arm-trusted-firmware.git

.
Random number generation is not supported on Stratix10 platform
But ATF code doesn't process properly and return error value.
So, make the workaround to avoid breaking ATF code.

Signed-off-by: Meng Li <Meng.Li@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
Signed-off-by: Liwei Song <liwei.song@windriver.com>