sf: Move SPI flash drivers to defconfig

There are already Kconfig options for SPI flash 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/T1024QDS_defconfig b/configs/T1024QDS_defconfig
index ea39baa..7bb2ea6 100644
--- a/configs/T1024QDS_defconfig
+++ b/configs/T1024QDS_defconfig
@@ -3,6 +3,9 @@
 CONFIG_TARGET_T102XQDS=y
 CONFIG_SYS_EXTRA_OPTIONS="PPC_T1024"
 CONFIG_SPI_FLASH=y
+CONFIG_SPI_FLASH_EON=y
+CONFIG_SPI_FLASH_STMICRO=y
+CONFIG_SPI_FLASH_SST=y
 CONFIG_NETDEVICES=y
 CONFIG_E1000=y
 CONFIG_SYS_NS16550=y