spi: Migrate CONFIG_KIRKWOOD_SPI to Kconfig

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
diff --git a/configs/netspace_mini_v2_defconfig b/configs/netspace_mini_v2_defconfig
index 76b09df..1012bea 100644
--- a/configs/netspace_mini_v2_defconfig
+++ b/configs/netspace_mini_v2_defconfig
@@ -30,4 +30,5 @@
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_MACRONIX=y
 CONFIG_SYS_NS16550=y
+CONFIG_KIRKWOOD_SPI=y
 CONFIG_OF_LIBFDT=y