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/P1010RDB-PA_36BIT_SPIFLASH_SECBOOT_defconfig b/configs/P1010RDB-PA_36BIT_SPIFLASH_SECBOOT_defconfig
index d8482a3..b24f704 100644
--- a/configs/P1010RDB-PA_36BIT_SPIFLASH_SECBOOT_defconfig
+++ b/configs/P1010RDB-PA_36BIT_SPIFLASH_SECBOOT_defconfig
@@ -34,6 +34,8 @@
 CONFIG_SYS_FLASH_USE_BUFFER_WRITE=y
 CONFIG_SYS_FLASH_CFI=y
 CONFIG_SPI_FLASH=y
+CONFIG_SF_DEFAULT_MODE=0
+CONFIG_SF_DEFAULT_SPEED=10000000
 CONFIG_SPI_FLASH_SPANSION=y
 CONFIG_PHY_MARVELL=y
 CONFIG_PHY_GIGE=y