ARM: zynq: Fix building SPL without FPGA support

ARM: zynq: Fix building SPL without FPGA support

When CONFIG_FPGA is defined but CONFIG_SPL_FPGA is not, the build fails:
board.c: In function 'board_init':
board.c:41:3: error: 'fpga' undeclared (first use in this function)
   fpga = fpga010;

Fix this by expanding the "#if.." around this block to match the other
FPGA checks and don't compile this block when buildign for SPL without
FPGA support.

Tested a bootloader that had CONFIG_FPGA defined without CONFIG_SPL_FPGA,
this now compiles without errors and loading FPGA from u-boot works.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>