Revert "arm: socfpga: set the fpga global bit to disable HPS to FPGA signals"

Revert "arm: socfpga: set the fpga global bit to disable HPS to FPGA signals"

Apparently, the logic for the FPGA global bit is not universal between Gen5
and Gen10 devices is not the same. Disabling this bit, while applicable to
Gen10 devices, will break FPGA programming on Gen5 devices.

Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>