Convert CONFIG_SF_DEFAULT_* to Kconfig

This converts the following to Kconfig:
  CONFIG_SF_DEFAULT_BUS
  CONFIG_SF_DEFAULT_CS
  CONFIG_SF_DEFAULT_MODE
  CONFIG_SF_DEFAULT_SPEED

I use moveconfig script and then manual check on generated u-boot.cfg
to solve the remaining issue.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
diff --git a/configs/ot1200_spl_defconfig b/configs/ot1200_spl_defconfig
index c8c53e8..d3960e4 100644
--- a/configs/ot1200_spl_defconfig
+++ b/configs/ot1200_spl_defconfig
@@ -42,6 +42,9 @@
 CONFIG_CMD_PCA953X=y
 CONFIG_FSL_ESDHC=y
 CONFIG_SPI_FLASH=y
+CONFIG_SF_DEFAULT_BUS=2
+CONFIG_SF_DEFAULT_MODE=0
+CONFIG_SF_DEFAULT_SPEED=25000000
 CONFIG_SPI_FLASH_MACRONIX=y
 CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SPI_FLASH_SST=y