FPGA: fix support for non-Lattice devices

FPGA: fix support for non-Lattice devices

Commit 3b8ac464 "FPGA: add support for downloading Lattice bitstream"
added support for Lattice devices, but failed to add #ifdef's that are
needed when building for non-Lattice devices, which results in build
failures like these:

Configuring for GEN860T board...
drivers/fpga/libfpga.a(fpga.o): In function `fpga_dev_info':
/home/wd/git/u-boot/work/drivers/fpga/fpga.c:145: undefined reference to `lattice_info'
drivers/fpga/libfpga.a(fpga.o): In function `fpga_dump':
/home/wd/git/u-boot/work/drivers/fpga/fpga.c:269: undefined reference to `lattice_dump'
drivers/fpga/libfpga.a(fpga.o): In function `fpga_load':
/home/wd/git/u-boot/work/drivers/fpga/fpga.c:233: undefined reference to `lattice_load'
make: *** [u-boot] Error 1

Add the missing code.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Stefano Babic <sbabic@denx.de>