spi: Migrate CONFIG_MXC_SPI to Kconfig

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
diff --git a/configs/pfla02_defconfig b/configs/pfla02_defconfig
index 488cf08..09efbcf 100644
--- a/configs/pfla02_defconfig
+++ b/configs/pfla02_defconfig
@@ -56,5 +56,6 @@
 CONFIG_PHY_MICREL_KSZ90X1=y
 CONFIG_NETDEVICES=y
 CONFIG_FEC_MXC=y
+CONFIG_MXC_SPI=y
 CONFIG_DM_THERMAL=y
 CONFIG_OF_LIBFDT=y