spi: Move SPI drivers to defconfig

There are already Kconfig options for SPI drivers, but we
have not moved them from config.h to defconfig files. This
commit does this in a batch.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/configs/snow_defconfig b/configs/snow_defconfig
index 41441a8..2b143ea 100644
--- a/configs/snow_defconfig
+++ b/configs/snow_defconfig
@@ -39,6 +39,7 @@
 CONFIG_I2S_SAMSUNG=y
 CONFIG_SOUND_MAX98095=y
 CONFIG_SOUND_WM8994=y
+CONFIG_EXYNOS_SPI=y
 CONFIG_TPM_TIS_INFINEON=y
 CONFIG_USB=y
 CONFIG_DM_USB=y