spi: xtensa-xtfpga: Enable driver compilation with COMPILE_TEST

This helps increasing build testing coverage.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
1 file changed