On ZynqMP the FSBL will configure the system counter. Hence, remove the
initialization of the system counter with hardcoded values from the ATF
and use the setup provided by the bootloader.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>