arm: socfpga: fix trivial header preprocessor for socfpga_common.h

Replace__CONFIG_SOCFPGA_CYCLONE5_COMMON_H__ with
__CONFIG_SOCFPGA_COMMON_H__ as the file is now called socfpga_common.h

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