spi: lantiq-ssc: activate under COMPILE_TEST

This driver should compile on all platforms, activate it under compile
test. The Lantiq specific parts are under ifdef and should be removed
when Lantiq platform supports common clock framework.
Signed-off-by: NHauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: NMark Brown <broonie@kernel.org>

drivers/spi/Kconfig

@@ -417,7 +417,7 @@ config SPI_NUC900
 
 config SPI_LANTIQ_SSC
 	tristate "Lantiq SSC SPI controller"
-	depends on LANTIQ
+	depends on LANTIQ || COMPILE_TEST
 	help
 	  This driver supports the Lantiq SSC SPI controller in master
 	  mode. This controller is found on Intel (former Lantiq) SoCs like