spi: Migrate CONFIG_CF_SPI to Kconfig

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>
diff --git a/configs/M54455EVB_stm33_defconfig b/configs/M54455EVB_stm33_defconfig
index fd36f22..32ad61b 100644
--- a/configs/M54455EVB_stm33_defconfig
+++ b/configs/M54455EVB_stm33_defconfig
@@ -26,3 +26,4 @@
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_SPI_FLASH=y
 CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_CF_SPI=y